Dup2 after fork in multithreaded application

I am working on a multithreaded application (C++) that must create several
Java processes and capture their output though pipes.
For a single threaded application, I know it is possible to call dup2 (in the child)
after the fork to set up the proper connections.
I am aware that it is not safe to make particular function calls between a fork
and an exec. Is dup2 a call that is known to be safe?
If not, is there a better alternative?
Thanks.

I'm using Oracle 10g2 on Windows Server 2003 on a Dell PowerEdge 1850 server.
Both threads run the same code. Each thread performs multiple database queries though.
This query is performed first:
update my_table set my_data_processed='true' where my_data_processed='false' and rownum=1 returning my_index into :x
Then the query with the getBlob is performed with <some_number> = my_index.
Some background info: I have a lot of data in my_table that needs a very slow operation performed on the my_data blob in each row. I will eventually run this application on multiple servers in parallel and need a way to determine the next row that hasn't been processed yet then process it.
The table is
create table my_table (
my_index int,
my_data_processed varchar(10),
my_data blob
-Glen

Similar Messages

Pro*c multithreaded application has memory leak

Hi there,
I posted this message a week ago in OCI section, nobody answer me.
I am really curious if my application has a bug or the pro*c has a bug.
Anyone can compile the sample code and test it easily.
I made multithreaded application which queries dynamic SQL, it works.
But the memory leaks when i query the SQL statement.
The more memory leaks, the more i query the SQL statement, even same SQL
statement.
I check it with top, shell command.
My machine is SUN E450, Solaris 8. Oracle 9.2.0.1
Compiler : gcc (GCC) 3.2.2
I changed source code which is from
$(ORACLE_HOME)/precomp/demo/proc/sample10.pc
the sample10 doesn't need to be multithreaded. But i think it has to work
correctly if i changed it to multithreaded application.
the make file and source code will be placed below.
I have to figure out the problem.
Please help
Thanks in advance,
the make file is below
HOME = /user/jkku
ORA = $(ORACLE_HOME)
CC = gcc
PROC = proc
LC_INCL = -I$(HOME)/work/dbmss/libs/include
lc_incl = include=$(HOME)/work/dbmss/libs/include
SYS_INCL =
sys_incl =
ORA_INCL = -I. \
-I$(ORA)/precomp/public \
-I$(ORA)/rdbms/public \
-I$(ORA)/rdbms/demo \
-I$(ORA)/rdbms/pbsql/public \
-I$(ORA)/network/public \
-DSLMXMX_ENABLE -DSLTS_ENABLE -D_SVID_GETTOD
INCLUDES = $(LC_INCL) $(SYS_INCL) $(ORA_INCL)
includes = $(lc_incl) $(sys_incl)
LC_LIBS =
SYS_LIBS = -lpthread -lsocket -lnsl -lrt
ORA_LIBS = -L$(ORA)/lib/ -lclntsh
LIBS = $(LC_LIBS) $(SYS_LIBS) $(ORA_LIBS)
# Define C Compiler flags
CFLAGS += -D_Solaris64_ -m64
CFLAGS += -g -D_REENTRANT
# Define pro*c Compiler flags
PROCFLAGS += THREADS=YES
PROCFLAGS += CPOOL=YES
# Our object files
PRECOMPS = sample10.c
OBJS = sample10.o
.SUFFIXES: .o .c .pc
.c.o:
$(CC) -c $(CFLAGS) $(INCLUDES) $*.c
.pc.c:
$(PROC) $(PROCFLAGS) $(includes) $*.pc $*.c
all: sample10
sample10: $(PRECOMPS) $(OBJS)
$(CC) $(CFLAGS) -o sample10 $(OBJS) $(LIBS)
clean:
rm -rf *.o sample10 sample10.c
the source code is below which i changed the oracle sample10.pc to
multithreaded application.
Sample Program 10: Dynamic SQL Method 4
This program connects you to ORACLE using your username and
password, then prompts you for a SQL statement. You can enter
any legal SQL statement. Use regular SQL syntax, not embedded SQL.
Your statement will be processed. If it is a query, the rows
fetched are displayed.
You can enter multi-line statements. The limit is 1023 characters.
This sample program only processes up to MAX_ITEMS bind variables and
MAX_ITEMS select-list items. MAX_ITEMS is #defined to be 40.
#include <stdio.h>
#include <string.h>
#include <setjmp.h>
#include <sqlda.h>
#include <stdlib.h>
#include <sqlcpr.h>
/* Maximum number of select-list items or bind variables. */
#define MAX_ITEMS 40
/* Maximum lengths of the names of the
select-list items or indicator variables. */
#define MAX_VNAME_LEN 30
#define MAX_INAME_LEN 30
#ifndef NULL
#define NULL 0
#endif
/* Prototypes */
#if defined(__STDC__)
void sql_error(void);
int oracle_connect(void);
int alloc_descriptors(int, int, int);
int get_dyn_statement(void);
void set_bind_variables(void);
void process_select_list(void);
void help(void);
#else
void sql_error(/*_ void _*/);
int oracle_connect(/*_ void _*/);
int alloc_descriptors(/*_ int, int, int _*/);
int get_dyn_statement(/* void _*/);
void set_bind_variables(/*_ void -*/);
void process_select_list(/*_ void _*/);
void help(/*_ void _*/);
#endif
char *dml_commands[] = {"SELECT", "select", "INSERT", "insert",
"UPDATE", "update", "DELETE", "delete"};
EXEC SQL INCLUDE sqlda;
EXEC SQL INCLUDE sqlca;
EXEC SQL BEGIN DECLARE SECTION;
char dyn_statement[1024];
EXEC SQL VAR dyn_statement IS STRING(1024);
EXEC SQL END DECLARE SECTION;
EXEC ORACLE OPTION (ORACA=YES);
EXEC ORACLE OPTION (RELEASE_CURSOR=YES);
SQLDA *bind_dp;
SQLDA *select_dp;
/* Define a buffer to hold longjmp state info. */
jmp_buf jmp_continue;
char *db_uid="dbmuser/dbmuser@dbmdb";
sql_context ctx;
int err_sql;
enum{
SQL_SUCC=0,
SQL_ERR,
SQL_NOTFOUND,
SQL_UNIQUE,
SQL_DISCONNECT,
SQL_NOTNULL
int main()
int i;
EXEC SQL ENABLE THREADS;
EXEC SQL WHENEVER SQLERROR DO sql_error();
EXEC SQL WHENEVER NOT FOUND DO sql_not_found();
/* Connect to the database. */
if (connect_database() < 0)
exit(1);
EXEC SQL CONTEXT USE :ctx;
/* Process SQL statements. */
for (;;)
/* Allocate memory for the select and bind descriptors. */
if (alloc_descriptors(MAX_ITEMS, MAX_VNAME_LEN, NAME_LEN) != 0)
exit(1);
(void) setjmp(jmp_continue);
/* Get the statement. Break on "exit". */
if (get_dyn_statement() != 0)
break;
EXEC SQL PREPARE S FROM :dyn_statement;
EXEC SQL DECLARE C CURSOR FOR S;
/* Set the bind variables for any placeholders in the
SQL statement. */
set_bind_variables();
/* Open the cursor and execute the statement.
* If the statement is not a query (SELECT), the
* statement processing is completed after the
* OPEN.
EXEC SQL OPEN C USING DESCRIPTOR bind_dp;
/* Call the function that processes the select-list.
* If the statement is not a query, this function
* just returns, doing nothing.
process_select_list();
/* Tell user how many rows processed. */
for (i = 0; i < 8; i++)
if (strncmp(dyn_statement, dml_commands, 6) == 0)
printf("\n\n%d row%c processed.\n", sqlca.sqlerrd[2], sqlca.sqlerrd[2] == 1 ? '\0' : 's');
break;
/* Close the cursor. */
EXEC SQL CLOSE C;
/* When done, free the memory allocated for pointers in the bind and
select descriptors. */
for (i = 0; i < MAX_ITEMS; i++)
if (bind_dp->V != (char *) 0)
free(bind_dp->V);
free(bind_dp->I); /* MAX_ITEMS were allocated. */
if (select_dp->V != (char *) 0)
free(select_dp->V);
free(select_dp->I); /* MAX_ITEMS were allocated. */
/* Free space used by the descriptors themselves. */
SQLSQLDAFree(ctx, bind_dp);
SQLSQLDAFree(ctx, select_dp);
} /* end of for(;;) statement-processing loop */
disconnect_database();
EXEC SQL WHENEVER SQLERROR CONTINUE;
EXEC SQL COMMIT WORK RELEASE;
puts("\nHave a good day!\n");
return;
* Allocate the BIND and SELECT descriptors using sqlald().
* Also allocate the pointers to indicator variables
* in each descriptor. The pointers to the actual bind
* variables and the select-list items are realloc'ed in
* the set_bind_variables() or process_select_list()
* routines. This routine allocates 1 byte for select_dp->V
* and bind_dp->V, so the realloc will work correctly.
alloc_descriptors(size, max_vname_len, max_iname_len)
int size;
int max_vname_len;
int max_iname_len;
int i;
* The first sqlald parameter determines the maximum number of
* array elements in each variable in the descriptor. In
* other words, it determines the maximum number of bind
* variables or select-list items in the SQL statement.
* The second parameter determines the maximum length of
* strings used to hold the names of select-list items
* or placeholders. The maximum length of column
* names in ORACLE is 30, but you can allocate more or less
* as needed.
* The third parameter determines the maximum length of
* strings used to hold the names of any indicator
* variables. To follow ORACLE standards, the maximum
* length of these should be 30. But, you can allocate
* more or less as needed.
if ((bind_dp =
SQLSQLDAAlloc(ctx, size, max_vname_len, max_iname_len)) ==
(SQLDA *) 0)
fprintf(stderr,
"Cannot allocate memory for bind descriptor.");
return -1; /* Have to exit in this case. */
if ((select_dp =
SQLSQLDAAlloc(ctx, size, max_vname_len, max_iname_len)) == (SQLDA *)
0)
fprintf(stderr,
"Cannot allocate memory for select descriptor.");
return -1;
select_dp->N = MAX_ITEMS;
/* Allocate the pointers to the indicator variables, and the
actual data. */
for (i = 0; i < MAX_ITEMS; i++) {
bind_dp->I = (short *) malloc(sizeof (short));
select_dp->I = (short *) malloc(sizeof(short));
bind_dp->V = (char *) malloc(1);
select_dp->V = (char *) malloc(1);
return 0;
int get_dyn_statement()
char *cp, linebuf[256];
int iter, plsql;
for (plsql = 0, iter = 1; ;)
if (iter == 1)
printf("\nSQL> ");
dyn_statement[0] = '\0';
fgets(linebuf, sizeof linebuf, stdin);
cp = strrchr(linebuf, '\n');
if (cp && cp != linebuf)
*cp = ' ';
else if (cp == linebuf)
continue;
if ((strncmp(linebuf, "EXIT", 4) == 0) ||
(strncmp(linebuf, "exit", 4) == 0))
return -1;
else if (linebuf[0] == '?' ||
(strncmp(linebuf, "HELP", 4) == 0) ||
(strncmp(linebuf, "help", 4) == 0))
help();
iter = 1;
continue;
if (strstr(linebuf, "BEGIN") ||
(strstr(linebuf, "begin")))
plsql = 1;
strcat(dyn_statement, linebuf);
if ((plsql && (cp = strrchr(dyn_statement, '/'))) ||
(!plsql && (cp = strrchr(dyn_statement, ';'))))
*cp = '\0';
break;
else
iter++;
printf("%3d ", iter);
return 0;
void set_bind_variables()
int i, n;
char bind_var[64];
/* Describe any bind variables (input host variables) */
EXEC SQL WHENEVER SQLERROR DO sql_error();
bind_dp->N = MAX_ITEMS; /* Initialize count of array elements. */
EXEC SQL DESCRIBE BIND VARIABLES FOR S INTO bind_dp;
/* If F is negative, there were more bind variables
than originally allocated by sqlald(). */
if (bind_dp->F < 0)
printf ("\nToo many bind variables (%d), maximum is %d\n.",
-bind_dp->F, MAX_ITEMS);
return;
/* Set the maximum number of array elements in the
descriptor to the number found. */
bind_dp->N = bind_dp->F;
/* Get the value of each bind variable as a
* character string.
* C contains the length of the bind variable
* name used in the SQL statement.
* S contains the actual name of the bind variable
* used in the SQL statement.
* L will contain the length of the data value
* entered.
* V will contain the address of the data value
* entered.
* T is always set to 1 because in this sample program
* data values for all bind variables are entered
* as character strings.
* ORACLE converts to the table value from CHAR.
* I will point to the indicator value, which is
* set to -1 when the bind variable value is "null".
for (i = 0; i < bind_dp->F; i++)
printf ("\nEnter value for bind variable %.*s: ",
(int)bind_dp->C, bind_dp->S);
fgets(bind_var, sizeof bind_var, stdin);
/* Get length and remove the new line character. */
n = strlen(bind_var) - 1;
/* Set it in the descriptor. */
bind_dp->L = n;
/* (re-)allocate the buffer for the value.
sqlald() reserves a pointer location for
V but does not allocate the full space for
the pointer. */
bind_dp->V = (char *) realloc(bind_dp->V, (bind_dp->L + 1));
/* And copy it in. */
strncpy(bind_dp->V, bind_var, n);
/* Set the indicator variable's value. */
if ((strncmp(bind_dp->V, "NULL", 4) == 0) ||
(strncmp(bind_dp->V, "null", 4) == 0))
*bind_dp->I = -1;
else
*bind_dp->I = 0;
/* Set the bind datatype to 1 for CHAR. */
bind_dp->T = 1;
return;
void process_select_list()
int i, null_ok, precision, scale;
if ((strncmp(dyn_statement, "SELECT", 6) != 0) &&
(strncmp(dyn_statement, "select", 6) != 0))
select_dp->F = 0;
return;
/* If the SQL statement is a SELECT, describe the
select-list items. The DESCRIBE function returns
their names, datatypes, lengths (including precision
and scale), and NULL/NOT NULL statuses. */
select_dp->N = MAX_ITEMS;
EXEC SQL DESCRIBE SELECT LIST FOR S INTO select_dp;
/* If F is negative, there were more select-list
items than originally allocated by sqlald(). */
if (select_dp->F < 0)
printf ("\nToo many select-list items (%d), maximum is %d\n",
-(select_dp->F), MAX_ITEMS);
return;
/* Set the maximum number of array elements in the
descriptor to the number found. */
select_dp->N = select_dp->F;
/* Allocate storage for each select-list item.
sqlprc() is used to extract precision and scale
from the length (select_dp->L).
sqlnul() is used to reset the high-order bit of
the datatype and to check whether the column
is NOT NULL.
CHAR datatypes have length, but zero precision and
scale. The length is defined at CREATE time.
NUMBER datatypes have precision and scale only if
defined at CREATE time. If the column
definition was just NUMBER, the precision
and scale are zero, and you must allocate
the required maximum length.
DATE datatypes return a length of 7 if the default
format is used. This should be increased to
9 to store the actual date character string.
If you use the TO_CHAR function, the maximum
length could be 75, but will probably be less
(you can see the effects of this in SQL*Plus).
ROWID datatype always returns a fixed length of 18 if
coerced to CHAR.
LONG and
LONG RAW datatypes return a length of 0 (zero),
so you need to set a maximum. In this example,
it is 240 characters.
printf ("\n");
for (i = 0; i < select_dp->F; i++)
char title[MAX_VNAME_LEN];
/* Turn off high-order bit of datatype (in this example,
it does not matter if the column is NOT NULL). */
sqlnul ((unsigned short *)&(select_dp->T), (unsigned short
*)&(select_dp->T), &null_ok);
switch (select_dp->T)
case 1 : /* CHAR datatype: no change in length
needed, except possibly for TO_CHAR
conversions (not handled here). */
break;
case 2 : /* NUMBER datatype: use sqlprc() to
extract precision and scale. */
sqlprc ((unsigned int *)&(select_dp->L), &precision,
&scale);
/* Allow for maximum size of NUMBER. */
if (precision == 0) precision = 40;
/* Also allow for decimal point and
possible sign. */
/* convert NUMBER datatype to FLOAT if scale > 0,
INT otherwise. */
if (scale > 0)
select_dp->L = sizeof(float);
else
select_dp->L = sizeof(int);
break;
case 8 : /* LONG datatype */
select_dp->L = 240;
break;
case 11 : /* ROWID datatype */
case 104 : /* Universal ROWID datatype */
select_dp->L = 18;
break;
case 12 : /* DATE datatype */
select_dp->L = 9;
break;
case 23 : /* RAW datatype */
break;
case 24 : /* LONG RAW datatype */
select_dp->L = 240;
break;
/* Allocate space for the select-list data values.
sqlald() reserves a pointer location for
V but does not allocate the full space for
the pointer. */
if (select_dp->T != 2)
select_dp->V = (char *) realloc(select_dp->V,
select_dp->L + 1);
else
select_dp->V = (char *) realloc(select_dp->V,
select_dp->L);
/* Print column headings, right-justifying number
column headings. */
/* Copy to temporary buffer in case name is null-terminated */
memset(title, ' ', MAX_VNAME_LEN);
strncpy(title, select_dp->S, select_dp->C);
if (select_dp->T == 2)
if (scale > 0)
printf ("%.*s ", select_dp->L+3, title);
else
printf ("%.*s ", select_dp->L, title);
else
printf("%-.*s ", select_dp->L, title);
/* Coerce ALL datatypes except for LONG RAW and NUMBER to
character. */
if (select_dp->T != 24 && select_dp->T != 2)
select_dp->T = 1;
/* Coerce the datatypes of NUMBERs to float or int depending on
the scale. */
if (select_dp->T == 2)
if (scale > 0)
select_dp->T = 4; /* float */
else
select_dp->T = 3; /* int */
printf ("\n\n");
/* FETCH each row selected and print the column values. */
EXEC SQL WHENEVER NOT FOUND GOTO end_select_loop;
for (;;)
EXEC SQL FETCH C USING DESCRIPTOR select_dp;
/* Since each variable returned has been coerced to a
character string, int, or float very little processing
is required here. This routine just prints out the
values on the terminal. */
for (i = 0; i < select_dp->F; i++)
if (*select_dp->I < 0)
if (select_dp->T == 4)
printf ("%-*c ",(int)select_dp->L+3, ' ');
else
printf ("%-*c ",(int)select_dp->L, ' ');
else
if (select_dp->T == 3) /* int datatype */
printf ("%*d ", (int)select_dp->L,
*(int *)select_dp->V);
else if (select_dp->T == 4) /* float datatype */
printf ("%*.2f ", (int)select_dp->L,
*(float *)select_dp->V);
else /* character string */
printf ("%-*.*s ", (int)select_dp->L,
(int)select_dp->L, select_dp->V);
printf ("\n");
end_select_loop:
return;
void help()
puts("\n\nEnter a SQL statement or a PL/SQL block at the SQL> prompt.");
puts("Statements can be continued over several lines, except");
puts("within string literals.");
puts("Terminate a SQL statement with a semicolon.");
puts("Terminate a PL/SQL block (which can contain embedded
semicolons)");
puts("with a slash (/).");
puts("Typing \"exit\" (no semicolon needed) exits the program.");
puts("You typed \"?\" or \"help\" to get this message.\n\n");
int connect_database()
err_sql = SQL_SUCC;
EXEC SQL WHENEVER SQLERROR DO sql_error();
EXEC SQL WHENEVER NOT FOUND DO sql_not_found();
EXEC SQL CONTEXT ALLOCATE :ctx;
EXEC SQL CONTEXT USE :ctx;
EXEC SQL CONNECT :db_uid;
if(err_sql != SQL_SUCC){
printf("err => connect database(ctx:%ld, uid:%s) failed!\n", ctx, db_uid);
return -1;
return 1;
int disconnect_database()
err_sql = SQL_SUCC;
EXEC SQL WHENEVER SQLERROR DO sql_error();
EXEC SQL WHENEVER NOT FOUND DO sql_not_found();
EXEC SQL CONTEXT USE :ctx;
EXEC SQL COMMIT WORK RELEASE;
EXEC SQL CONTEXT FREE:ctx;
return 1;
void sql_error()
printf("err => %.*s", sqlca.sqlerrm.sqlerrml, sqlca.sqlerrm.sqlerrmc);
printf("in \"%.*s...\'\n", oraca.orastxt.orastxtl, oraca.orastxt.orastxtc);
printf("on line %d of %.*s.\n\n", oraca.oraslnr, oraca.orasfnm.orasfnml,
oraca.orasfnm.orasfnmc);
switch(sqlca.sqlcode) {
case -1: /* unique constraint violated */
err_sql = SQL_UNIQUE;
break;
case -1012: /* not logged on */
case -1089:
case -3133:
case -1041:
case -3114:
case -3113:
/* �6�Ŭ�� shutdown�ǰų� �α�� °� �ƴҶ� ��b�� õ� */
/* immediate shutdown in progress - no operations are permitted */
/* end-of-file on communication channel */
/* internal error. hostdef extension doesn't exist */
err_sql = SQL_DISCONNECT;
break;
case -1400:
err_sql = SQL_NOTNULL;
break;
default:
err_sql = SQL_ERR;
break;
EXEC SQL CONTEXT USE :ctx;
EXEC SQL WHENEVER SQLERROR CONTINUE;
EXEC SQL ROLLBACK WORK;
void sql_not_found()
err_sql = SQL_NOTFOUND;

Hi Jane,
What version of Berkeley DB XML are you using?
What is your operating system and your hardware platform?
For how long have been the application running?
What is your current container size?
What's set for EnvironmentConfig.setThreaded?
Do you know if containers have previously not been closed correctly?
Can you please post the entire error output?
What's the JDK version, 1.4 or 1.5?
Thanks,
Bogdan

How to Debug C++ Multithreaded Application in Solaris

Hi All,
I am working in Solaris Sparc 5.8 Machine. I need to debug Multithreaded C++ Application in Unix Environment.
I am using dbx debugger.
Please explain me how to debug multithreaded applications. if possible please explain me with example.
Thanks in Advance.
Thanks & Regards,
Vasu

1. Look over the dbx manual that comes with Sun Studio. Dbx includes many features for debugging MT code.
2. If you have specific questions after reading the manual and trying out the features, ask them in the debugger forum:
http://forum.sun.com/forum.jspa?forumID=257

PersistenceManager Patterns for Multithreaded Applications

Hi,
I'm looking for a good way, how to use Kodo JDO in a multithread application
(actually Tomcat ;). The most easy thing is perhaps, to use only one
persistence
manager for the entire application, i.e. for all threads. Another solution
might be,
to create a PersistenceManager for each HTTP request. I don't like the
solution,
to have one PeristenceManager per session, because I expect thousands
concurrent
users. What I'm concerned with is the number of data base connections in
this
case.
So my question to you is, what pattern do you use in your web applications?
When do you create and close the PersistenceManagers to free resources?
Has anybody alreay tried different patterns and compared the performance?
Is there something like a best practice?
Michael

The other nice thing about the filter is that it should be easy to
selectivly store and retrieve the PM in a user's session if they have a
longer running transaction that spans multiple requests.
So far, I've simply been passing the PM to each service method, although I
don't particularliy like that approach. I haven't had time to try anything
different yet and it isn't TOO bad, although I have a few ideas:
1. The hashtable method you mentioned. I see there is a "Registry" pattern
in the "Patterns of Enterprise Application Architecture" book I'm currently
reading, but haven't gotten to it yet. I think it is close to what you
mentioned.
2. Retrieve the PM through JNDI. I don't know, however, if I can set up a
PM in JNDI the way that the CurrentTransaction JNDI lookup works with
container managed transactions.
"Michael" <[email protected]> wrote in message
news:[email protected]...
I've never used a servlet filter before but I must say that is the most
elegant approach I've seen, thanks for sharing that. How do you pass thePM
to the service layer? Do you store it in a hashtable with the current
thread as a key or do you pass it in to each service method?
Thanks,
Michael
"Nathan Voxland" <[email protected]> wrote in message
news:[email protected]...
We've created the PersistenceManager in a filter and attached it to the
request object. That way, the persistence manager can be accessed fromthe
Struts Action, JSP Page, and anything else we do, plus we don't have to
worry about closing it because it is closed by the filter after
everything
is done (Even if an exception is thrown)
Here is the code:
public void doFilter(final ServletRequest request, final ServletResponse
response, FilterChain chain) throws IOException, ServletException {
PersistenceManager pm = getPersistenceManager();
request.setAttribute(JDO_PERSISTENCE_MANAGER, pm);
try {
chain.doFilter(request, response);
} finally {
if (pm.currentTransaction().isActive()) {
pm.currentTransaction().rollback();
pm.close();
"Michael" <[email protected]> wrote in message
news:[email protected]...
I currently doing exactly this: getting a persistence manager at the
beginning of a jsp page and close it at the end of the jsp page.
When you use <jsp:include ...>, you must be careful not to close the
persistence manager to early. I do it like this:
This sounds like a good approach, especially the hashtable with the
thread
as the key. The only issue I see is if you create the PM in the JSPpage,
often an Action is executed before the JSP is called. This is why I
was
thinking of creating the PM in the struts request processor, it'salways
called for every request.

Consuming a jms queue from a multithread application

Hi
Thank you for reading my post.
I have an application which shuld consume message of a queue.
my application is multithread and what i want to know is:
- How i can ask queue to remove a message after my thread finished its work with the message, by this way i can ensure that if my thread face an exception after it read the message my message will not lose.
- As it is multithread application, How i can ensure that a message is not delivered to two or more thread? is there any way to consume the messages in a synchronized way?
Will synchronized access restrict the performance?
Thanks

This is running in a J2DK environment. For my thread pool, I just copied one from a Sun tutorial on multi-threading then modified it. I creaed a seperate package with three classes. Here is my thread pooling package. I basically use a Vector to hold threads when they are not working. And you can set a limit as to the max number of active threads.
package threadpooling;
* @author cferris
* This class is simple to wrap the runnable
* thread for the worker thread around other
* needed parameters like salon id and source.
public class TaskWrapper {
// Define the needed instance fields.
public Runnable taskAtHand = null;
public String taskType = "";
    // Overloaded constructor.
    public TaskWrapper(Runnable task) {
      // Just set the runnable
      taskAtHand = task;
      taskType = "WorkerThread";
    } // of overloaded contructor
    // Overloaded constructor.
    public TaskWrapper(Runnable task, String taskType) {
      // Just set the instance fields
      taskAtHand = task;
      this.taskType = taskType;
    } // of overloaded contructor
package threadpooling;
* @author cferris
* This class is for tracking the number of
* active threads so we don't go over the set
* limit. This class basically synchronizes
* the methods that update the active thread
* counter.
import java.util.*;
public class ThreadPool {
// Define the instance fields.
//   First define instance fields for the
//   management of the thread pools - pm.
protected Vector poolOfThreads = new Vector();
private static LinkedList taskQueue = new LinkedList();
private static int poolSize = 0;
private static boolean pmAvailable = true;
private static boolean daemon = false;
public   static boolean shutDown = false;
//   Instance field for the management of
//   the threads - tm.
private static int activeThreads = 0;
private static int maxReached = 0;
private static int numTimesReached = 0;
private static boolean tmAvailable = true;
// Define constants
private static final int MAX_LIMIT_DEFAULT = 32;
    // The constructor.
    public ThreadPool() {
      this(MAX_LIMIT_DEFAULT, false);
    } // of constructor
    // Overload the constructor with max number of active jobs.
    public ThreadPool(int poolSize, boolean daemon) {
      this.poolSize = poolSize;
      this.daemon = daemon;
      poolOfThreads = new Vector();
      taskQueue = new LinkedList();
      salonTracker = new Vector();
      // Load up and initialize the threads.
      for (int i=0; i < poolSize; i++) {
          Thread thread = new WorkerThread(this, i);
          thread.setDaemon(daemon);
          thread.start();
          poolOfThreads.add(thread);
    } // of overloaded constructor
    // Overload this method to allow just the runnable task.
    public void assignWork(Runnable work) {
      // Create the wrapper
      TaskWrapper wrapper = new TaskWrapper(work, "A task");
      assignWork(wrapper);
    } // of overloaded assignWork
    // Push a unit of work (work thread) on the the worker thread.
    public synchronized void assignWork(TaskWrapper work) {
      // First increament the active thread count.
      increment();
      // Wait until we can access the linked list
      try {
          if (!pmAvailable)
              wait();
      } catch(InterruptedException e) { }
      pmAvailable = false;
      notifyAll();
      taskQueue.addLast(work);
      pmAvailable = true;
      notifyAll();
    } // of assignWork
    // Get the next unit of work (work thread).
    public synchronized TaskWrapper getNextWorkAssignment() {
      // Wait until we can access the linked list
      try {
          if (!pmAvailable)
              wait();
      } catch(InterruptedException e) { }
      pmAvailable = false;
      notifyAll();
      TaskWrapper nextTask;
      if (!taskQueue.isEmpty())
          nextTask = (TaskWrapper)taskQueue.removeFirst();
      else
          nextTask = null;
      pmAvailable = true;
      notifyAll();
      return nextTask;
    } // of getNextWorkAssignment
    // Return the number of tasks waiting on the work queue.
    public synchronized int workWaiting() {
      // Wait until we can access the linked list
      try {
          if (!pmAvailable)
              wait();
      } catch(InterruptedException e) { }
      pmAvailable = false;
      notifyAll();
      int qSize = taskQueue.size();
      pmAvailable = true;
      notifyAll();
      return qSize;
    } // of workWaiting
    // Wait until all the tasks have been completed.
    public void waitForCompletion() {
      int prev = 0;
      // Continue checking untill all the threads have
      // completed and been removed.
      while(!poolOfThreads.isEmpty()) {
         // Lets record the difference
         if (poolOfThreads.size() != prev) {
             System.out.println("waiting for " + poolOfThreads.size() + " to complete");
             prev = poolOfThreads.size();
         // Loop through the thread pool and check each thread.
         for (int t = 0; t < poolOfThreads.size(); t++)
              if (!((WorkerThread)poolOfThreads.get(t)).working)
                  // This thead is done so remove it.
                  poolOfThreads.remove(t);
      } // of while
    } // waitForCompletion
    // Set the max number of allow threads.
    public synchronized void setPoolSize(int newLimit) {
      // just set the limit.
      // Check if available
      while (!tmAvailable) {
         try {
           wait();
         catch(InterruptedException ie) {
           System.exit(5);
      // Ok, lock the object while we update it.
      tmAvailable = false;
      notifyAll();
      poolSize = newLimit;
      // Reset the max counters/trackers too
      maxReached = 0;
      numTimesReached = 0;
      // Create additional threads in the pool if needed
      if (poolSize > poolOfThreads.size())
          // Load up and initialize the threads.
          for (int i = poolOfThreads.size(); i < poolSize; i++) {
              Thread thread = new WorkerThread(this, i);
              thread.start();
              poolOfThreads.add(thread);
      // Done, now release the object.
      tmAvailable = true;
      notifyAll();
    } // of setPoolSize.
    // The method to increment thread counter.
    private synchronized void increment() {
      // Check if available
      while (!tmAvailable) {
         try {
           wait();
         catch(InterruptedException ie) {
           // logger.fatal("Synchronized error in ThreadPool ");
           // logger.fatal("Error message is: " + ie.getMessage());
           System.exit(5);
      // Ok, lock the object while we update it.
      tmAvailable = false;
      notifyAll();
      activeThreads++;
      // Check if this is the highest number of threads
      // that has been active, if not then set so.
      if (activeThreads > maxReached)
          maxReached = activeThreads;
      if (activeThreads == poolSize)
          numTimesReached++;
      // Done, now release the object.
      tmAvailable = true;
      notifyAll();
    } // of increment
    // The method to increment thread counter.
    public synchronized void decrement() {
      // Check if available
      while (!tmAvailable) {
         try {
           wait();
         catch(InterruptedException ie) {
           // logger.fatal("Synchronized error in ThreadPool ");
           // logger.fatal("Error message is: " + ie.getMessage());
           System.exit(5);
      // Ok, lock the object while we update it.
      tmAvailable = false;
      notifyAll();
      activeThreads--;
      // Done, now release the object.
      tmAvailable = true;
      notifyAll();
    } // of decrement
    // A method to determine if the maximum number of active
    // threads has been reached.
    public synchronized boolean limitNotReached() {
      boolean limit = false;
      // Check if available
      while (!tmAvailable) {
         try {
           wait();
         catch(InterruptedException ie) {
           // logger.fatal("Synchronized error in ThreadPool.");
           // logger.fatal("Error message is: " + ie.getMessage());
           System.exit(5);
      // Ok, lock the object while we update it.
      tmAvailable = false;
      notifyAll();
      if (activeThreads < poolSize)
         limit = true;
      // Done, now release the object.
      tmAvailable = true;
      notifyAll();
      return limit;
    } // of limitNotReached
    // A method to return the number of active threads.
    public synchronized int currentNum() {
      // Check if available
      while (!tmAvailable) {
         try {
           wait();
         catch(InterruptedException ie) {
           // logger.fatal("Synchronized error in ThreadPool");
           // logger.fatal("Error message is: " + ie.getMessage());
           System.exit(5);
      // Ok, lock the object while we update it.
      tmAvailable = false;
      notifyAll();
      int numberOf = activeThreads;
      // Done, now release the object.
      tmAvailable = true;
      notifyAll();
      return numberOf;
    } // of currentNum
package threadpooling;
* @author cferris
*   This is the work thread that receives the
*   taskes or unit of work that make up the
*   thread pool.
public class WorkerThread extends Thread {
// Define need instance fields.
public boolean working = true;
public int id = 0;
private int pauseFactor = 1;
// The thread pool that this object belongs to.
public ThreadPool owner;
// Define the constructor for the seperate thread.
public WorkerThread(ThreadPool pooler, int id) {
    owner = pooler;
    this.id = id;
} // of contructor
// Wait for work or for system shutdown.
public void run() {
    // Define the work object.
    TaskWrapper unitOfWork = null;
    // Wait for work or until system is shutting down.
    do {
       unitOfWork = owner.getNextWorkAssignment();
       if (unitOfWork != null) {
           // First set name and then add salon to watch list.
           String taskName = unitOfWork.taskType + "-" + id;
           setName(taskName);
        // System.out.println("Starting thread - " + getName());
           unitOfWork.taskAtHand.run();
           // Done, now adjust tracker and reset the pause factor.
           owner.decrement();
           pauseFactor = 1;
       else {
           // No work so pause a bit
           try {
               sleep(150 * pauseFactor);
           } catch (InterruptedException e) { }
           // If consecutively pausing because of no work then
           // increase the pause time up to a point.
           if (pauseFactor < 49)
               pauseFactor++;
    } while (!owner.shutDown);
    // Set indicator this thread in the pool is done.
    working = false;
} // of run
}To use the thread pool just create a static instance of the ThreadPool in your main class
private static ThreadPool threadPool = new ThreadPool(getMaxThreads(), useDaemon());Then to launch a new thread use this.
    if (runOnSeperateThread()) {
        WriteTransThread task = new WriteTransThread(messasge);
        // Add to the thread pool.
        threadPool.assignWork(new TaskWrapper(task, "my thread"));
private boolean runOnSeperateThread() {
    // First check if mutli threading is turned on
    // and if there are open threads.
    if (multiThreadingOn && threadPool.limitNotReached())
        // Yes, there are open threads.
        return true;
    // Check if we can wait for an open thread.
    if (!multiThreadingOn || !waitForOpenThread)
        // No multi threading or waiting allowed.
        return false;
    // OK, wait for an open thread, wait for up
    // to 90 seconds.
    int j = 0;
    do {
        try {
            // Wait 1/2 a second.
            Thread.sleep(500);
        } catch(InterruptedException ignore) { };
        // Check again for an optn thread.
        if (threadPool.limitNotReached())
            // Ok to run on separate thread.
            return true;
        // Increament counter and wait again.
        j++;
    } while(j < 180);
    // If we got this far then we've waited long enough.
    logger.warn("Reached limit on waiting for an open thread in the pool");
    return false;
} // of runOnSeperateThreadThe WriteTransThread is a class that will extract the message body and write out its data to a table.
Last, before you end your program make sure all the threads have competed by calling the following.
// If multi-threading is activated then this method will
// wait for them to complete before returning. The
// max wait time is 300 secs or 5 minutes.
private void waitForThreadsToComplete(String message) {
    // First check for multi threading.
    if (prop.useMultiThread() && (threadPool.currentNum() > 0)) {
        int limit = 0;
        // Some threads are still active, wait
        logger.info("Waiting for threads to complete before " + message
                  + " current thread count is " + threadPool.currentNum());
        do {
           limit++;
           try {
               Thread.sleep(500); // Sleep 1/2 a sec.
           } catch(InterruptedException ie) { } // Ignore the error for now.
           // Max waith is 300 sec or 5 min.
        } while ((threadPool.currentNum() > 0) && (limit < 600));
} // of waitForThreadsToComplete

I/O Exception in multithreading application

I have a multithreading application that utilizes OracleDataSource with explicit caching enabled. The cache is sized to keep as little opened connections as possible. It works fine but under heavy load I'm getting
I/O Exception: The Network Adapter could not establish the connection(SQL Code: 17002, SQL State: + 08006) (java.sql.SQLRecoverableException)
oracle.jdbc.driver.SQLStateMapping:101 (null)
I suppose that this is due to numerous concurrent calls to Oracle listener which the last is unable to process. The database itself is OK as when opening the same number (and even times more) of connections sequentially we get no errors.
Is it possible to slow down OracleDataSource somehow to dose new physical connection requests?
ConnectionWaitTimeout is not an option as it dilays ALL connection requests thus after this timeout listener accepts that calls again with the same rate.
Actually I'm ready to give up some speed to get better reliability.

It means the file is not there. Check to make sure the file is in the specified location, if it is, check the spelling.

Ref T validity after fork ???

Hi,
Currently I am empirically trying to establish what the validity of a Ref to an object would be set in a parent, after a fork call in Unix but am not comfortable with this way of engineering :-) Can anyone please cast some light on what can and what cannot be asserted on Ref's after a fork call. My assessment is that the memory in the cache occupied by a pinned Ref will have the copy on write flag set and as such, if the parent tinkers with it, the child will get its own copy. If my assumption is correct that one cannoty safely maintain using an Oracle connection after forking and that Ref's are valid only within the context of a connection and that a child opens its own connection to Oralce (shared server instance) then I am lead to believe that the Ref will become unsafe to use especially if it was not pinned but attempted to be pinned in the child. If it was pinned before forking, read-only access should be fine (due to copy on write pages) but modifying it is not safe as the connection it lives in is not valid in the child. Can someone verify whether my assessment is correct ?
PS. we cannot write a multi-threaded application for various other reasons and we have to fork

Hi,
That crash looks like one where Safari has been modified by Safari Enhancer. This changes some internals of Safari resulting in the 10.4.11 updater not working to plan.
Download the 10.4.11 combo updater (from the Downloads link at the top of this page) and then download [Pacifist|www.charlessoft.com] to extract the Safari package from the updater. Use this to replace your broken Safari.app package.
Hope that works!

Problems after fork

Hello specialists,
I hope this is the right forum to get some help on a very dubious problem.
We created a very little C-library to use Unix-Calls in our JAVA-application. What we wanted to use especially is fork!
Now there is the following problem:
If the Java-application is "complicated enough" - whatever this is - then one or both processes (in most cases the childprocess) crash on one of the next few JAVA-lines of code after fork comes back.
Does anyone have similar problems or does anyone have an idea for a solution?
I can't post the JAVA-code because - as I said - the code-points where the dump occurs are not really important. Just the whole application must be complicated enough and so there is not really something like a minimal example.
I can try to post the C-code if this would help, because its not really very much.
I hope you can give me hints, because I got stuck after hundreds and hundreds of experiments.
Thanks in advance and
greetings from
Holger

Well after all that writing, I found an answer.
My previous searches were limited to 90 days. When I expanded that to cover the whole year, this is what I came up with...
It could be a InputManagers problem.
Quit Safari and go to these two locations and move anything in the folders to your Desktop.
HD/Users/yourhome/Library/InputManagers
HD/Library/InputManagers
That fixed the problem.

How to configure ENV and DB for multithreaded application?

Hi,
From document, I know DB_THREAD must be checked for both ENV and DB, but , I don't know which one is best choice for multithreaded application while facing DB_INIT_LOCK and DB_INIT_CDB. In my application, there maybe multi readers and writers at the same time, should I use DB_INIT_LOCK instead of DB_INIT_CDB? what other flags should I use?
DB_INIT_CDB provides multiple reader/single writer access while DB_INIT_LOCK should be used when multiple processes or threads are going to be reading and writing a Berkeley DB database.
Thanks for your seggestions and answers.

Thanks for the explanation,
The Berkeley DB Concurrent Data Store product
allows for multiple reader/single writer access
to a database. This means that at any point in time,
there may be either multiple readers accessing a
database or a single writer updating the database.
Berkeley DB Concurrent Data Store is intended for
applications that need support for concurrent updates
to a database that is largely used for reading.
If you are looking to support multiple readers and
multiple writers then take a look at the Transactional
Data Store product
(http://download.oracle.com/docs/cd/E17076_02/html/programmer_reference/transapp.html)
In this case the Environment is typically opened with:
DB_INIT_MPOOL, DB_INIT_LOCK, DB_INIT_LOG, and DB_INIT_TXN.
Let me know if I missed any of your question.
Thanks,
Sandra

Had Photoshop Elements 12 on my other Mac that recently got smashed, new one has no CD drive. How do I install Elements with my product key? Purchasing an external CD drive is not an option at this time after forking over the 2500 for the new Mac...

Had Photoshop Elements 12 on my other Mac that recently got smashed, new one has no CD drive. How do I install Elements with my product key? Purchasing an external CD drive is not an option at this time after forking over the 2500 for the new Mac...

Downloads available:
Suites and Programs: CC 2014 | CC | CS6 | CS5.5 | CS5 | CS4 | CS3
Acrobat: XI, X | 9,8 | 9 standard
Premiere Elements: 12 | 11, 10 | 9, 8, 7
Photoshop Elements: 12 | 11, 10 | 9,8,7
Lightroom: 5.6| 5 | 4 | 3
Captivate: 8 | 7 | 6 | 5
Contribute: CS5 | CS4, CS3
Download and installation help for Adobe links
Download and installation help for Prodesigntools links are listed on most linked pages. They are critical; especially steps 1, 2 and 3. If you click a link that does not have those steps listed, open a second window using the Lightroom 3 link to see those 'Important Instructions'.

Using time() function in multithreaded application

I am using time() function in a multithreaded application with NULL argument for getting current time.
Some time it's observed that we get a time one minute earlier than current time (3600 seconds).
Is there a problem in the usage of the function?
I am using expression : currenttime = time(NULL);
I had seen some people using following way - time(&currenttime );
Will above two behaves differently in multithreaded environment?
[I am using Sun C++ 5.5 compiler on Solaris 8]

How do you compare actual time against the time seen by your threads? If your threads are printing the value from time(2) to stdout, it's possible that you're seeing an artifact of thread scheduling and/or output buffering.
I really doubt that you have a concurrency problem, but anyway make sure that you include the -mt option on your compile line:
CC -mt blahblahblah...

Hi im from oman, muscat my friend and i bought ip5 last month her phone has facetime and mine is missing. I went back to Extra store and availed apple product packages but after availing t, facetime application was not installed.How to install facetime?

My serial number is C3******TWD, hi im from oman, muscat my friend and i bought ip5 last month her phone has facetime and mine is missing. I went back to Extra store and availed apple product packages but after availing t, facetime application was not installed.How to install facetime?
<Edited by Host>

Guys thank you so much for the advises and helps.. i went back to Extra store and finally they changed my unit to a new one..Now i can figured out which one has facetime or none, from the box itself at back it writtens arabic so definetely no facetime and if english, portugese and chinese characters has 100 % with facetime.. I'm so blessed that they agreed to changed my unit to new one. At first the manager opened four boxes of new unit for me to check if facetime is there and he reassured me there's new batch of iphone5 coming on 2nd day. So i went back and he changed it to new one.. .Now im satisfied..

Acrobat 8 Professional crashes 10 seconds after you start the application xp

Acrobat 8 Professional crashes 10 seconds after you start the application. I have adobe acrobat 8.1 running on a dell vostro 1400 vista.

Are you sure it's crashed and not 'temporarily-frozen'?
I'm having this issue with Acrobat 9, in which it launches and runs long enough to page down two times and then stops responding for about 30 seconds.

Unable to OPen Forms in a DR environment after logging in to Applications

Hi,
We are testing our DR(XP machines are part of the VMWare environment and the AIX OSes are on LPARs ) scenario and we were able to recover DB on DR database from production and had Application Code trees from prod...(Environment:AIX 64 BIT Powersystems, 11.5.10.2, 10.2.0.4)
We are able to startup DB,Applicaiton services on DR site. After logging in to applications environement...we are able to open up Applicaiton manager/portal based responsibilities but not able to open forms. I dont see the jinitiator popup wizzard when opening the forms...(we ensured that there is java installed on the machine,no popup blockers)...
Would appreciate your help and suggestions.
Thanks,
Hari

Hi Hussein,
Fyi, the Apache log had errors when run in configtest
Syntax error on line 17 of /.../iAS/Apache/modplsql/cfg/plsql_pls.conf:
Cannot load /..../iAS/Apache/modplsql/bin/modplsql.so into server: 0509-130 Symbol resolution failed for /..../iAS/lib/libclntsh.a(shr.o) because:
0509-136 Symbol pw_post (number 261) is not exported from
dependent module /unix.
0509-136 Symbol pw_wait (number 262) is not exported from
dependent module /unix.
0509-136 Symbol pw_config (number 263) is not exported from
dependent module /unix.
0509-136 Symbol aix_ora_pw_version3_required (number 264) is not exported from
dependent module /unix.
0509-022 Cannot load module /..../iAS/Apache/modplsql/bin/modplsql.so.
0509-026 System error: Cannot run a file that does not have a valid format.
0509-192 Examine .loader section symbols with the
'dump -Tv' command.
adapcctl.sh: exiting with status 8
This issues got resolved after running rootpre.sh
Appreciate your quick response and all the help.
Thanks,
Hari

There is no skype icon after i go onto application...

i downloaded skype on my macbook pro. after i did it told me to move my cursor to the applications icon and double click on it. after i did, i was unsure on what to do. it doesnt show a skype icon to go on and login and start using it. it had nothing related to skype infact, just some downloads and things. it shows on a skype help website that there should be a skype icon after you go on application, but not for me. as i said just random and typical things.
if you could help out that would be great.

The padlock is no longer part of Firefox; it was removed beginning in Firefox 4. The padlock shows that there is a secure connection but does not supply additional information. You could have made a typographical error and still have been connected to a secure connection. The padlock was replaced with the Site Identity Button (first appeared in Firefox 3). Familiarize yourself with the Site Identity Button at the left end of the Location Bar:
*https://www.mozilla.com/en-US/firefox/security/identity/
*https://support.mozilla.com/en-US/kb/Site+Identity+Button
*http://www.dria.org/wordpress/archives/2008/05/06/635/
You can install this add-on if you wish:
*https://addons.mozilla.org/en-US/firefox/addon/padlock-icon/
'''If this reply solves your problem, please click "Solved It" next to this reply when <u>signed-in</u> to the forum.'''

Dup2 after fork in multithreaded application

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