OCI Application with 1000 threads

Question

Hi All,
I just created a simple OCI program which creates 500 threads (using OCIThreadCreate call) . The threads do nothing except sleeping for sometime and then exitting. After some threads are spawned (number very non-deterministic) the application aborts. The debugger say the segv was received in pthread_join indicating some problem in OCIThreadJoin. Anyone having seen similar issues and would like to share thought/suggestions here would be great. Amazingly, the application runs well with number of threads set to 301. If this number is increased to 302, thats when the application starts aborting. The machine I am using is a linux machine with a reasonably good configuration so I dont think number of processes etc could be an issue here.
Any inputs ? Bug in OCI ?
Thanks,
Sumit

Answer 1

Actually, there is quite a huge bug in my sample code (which also exists in the original post). There is no counter for the actual number of threads created. The reason the crash is happening on pthread_join (both naturally and beneath OCI) is because we're trying to join threads which haven't been created.
Corrected code, with a thread counter, resides below:
/* ========================================================================= */
/* -- INCLUSIONS ----------------------------------------------------------- */
/* ========================================================================= */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <pthread.h>
#include "oci.h"
#include "oratypes.h"
/* ========================================================================= */
/* -- DEFINITIONS ---------------------------------------------------------- */
/* ========================================================================= */
#define MAX_THREADS 1000
/* ========================================================================= */
/* -- GLOBALS -------------------------------------------------------------- */
/* ========================================================================= */
int last_created_thread = 0;
OCIEnv *envhp = (OCIEnv *) 0;
/* ========================================================================= */
/* -- LOCAL FUNCTIONS ------------------------------------------------------ */
/* ========================================================================= */
void
thread_func_oci (void *args)
    int p1 = (int) args;
    printf("Thread %d: Entering %s()\n", p1, __FUNCTION__);
    fflush(stdout);
    sleep(5);
    printf("Thread %d: Waiting %s()\n", p1, __FUNCTION__);
    fflush(stdout);
    sleep(5);
    printf("Thread %d: Exiting %s()\n", p1, __FUNCTION__);
    fflush(stdout);
void *
thread_func_pth (void *args)
    int p1 = (int) pthread_self();
    printf("Thread %d: Entering %s()\n", p1, __FUNCTION__);
    fflush(stdout);
    sleep(5);
    printf("Thread %d: Waiting %s()\n", p1, __FUNCTION__);
    fflush(stdout);
    sleep(5);
    printf("Thread %d: Exiting %s()\n", p1, __FUNCTION__);
    fflush(stdout);
    return NULL;
void
create_threads_oci (int num_threads)
    sword               status;
    OCIError           *errhp;
    OCIThreadId        *thr_id[MAX_THREADS];
    OCIThreadHandle    *thr_hp[MAX_THREADS];
    int                 j = 0;
    int                 arr[MAX_THREADS];
    /* Initialize our thread counter */
    last_created_thread = 0;
    status = OCIEnvCreate(&envhp, OCI_THREADED, 0, 0, 0, 0, 0, 0);
    if (status != OCI_SUCCESS)
        printf("Error EnvCreate\n");
        exit(1);
    status = OCIHandleAlloc(envhp, (void **) &errhp, OCI_HTYPE_ERROR, 0, 0);
    if (status != OCI_SUCCESS)
        printf("Could not create error handle \n");
        exit(1);
    status = OCIThreadInit(envhp, errhp);
    if (status != OCI_SUCCESS)
        printf("Error: ThreadInit");
    for (j = 0; j < num_threads; j++)
        status = OCIThreadIdInit(envhp, errhp, &thr_id[j]);
        OCIThreadHndInit((dvoid *) envhp, (OCIError *) errhp,
                         (OCIThreadHandle **) & (thr_hp[j]));
    for (j = 0; j < num_threads; j++)
        status = OCIThreadCreate((dvoid *) envhp, (OCIError *) errhp,
                                 thread_func_oci, (dvoid *) & (arr[j]),
                                 (OCIThreadId *) thr_id[j],
                                 (OCIThreadHandle *) thr_hp[j]);
        if (status != OCI_SUCCESS)
            printf("last_created_thread = %d :: j = %d\n", last_created_thread, j);
            fflush(stdout);
            break;
        else
            last_created_thread = j;
    for (j = 0; j <= last_created_thread; j++)
        status = OCIThreadJoin((dvoid *) envhp, (OCIError *) errhp,
                               (OCIThreadHandle *) thr_hp[j]);
        status = OCIThreadClose((dvoid *) envhp, (OCIError *) errhp,
                                (OCIThreadHandle *) thr_hp[j]);
        status = OCIThreadIdDestroy((dvoid *) envhp, (OCIError *) errhp,
                                    (OCIThreadId **) & (thr_id[j]));
        status = OCIThreadHndDestroy((dvoid *) envhp, (OCIError *) errhp,
                                     (OCIThreadHandle **) & (thr_hp[j]));
    status = OCIThreadTerm((dvoid *) envhp, (OCIError *) errhp);
void
create_threads_pth (int num_threads)
    int                 status;
    pthread_t           thr_hp[MAX_THREADS];
    int                 j = 0;
    /* Initialize our thread counter */
    last_created_thread = 0;
    for (j = 0; j < num_threads; j++)
        status = pthread_create(&thr_hp[j], NULL, thread_func_pth,
                                    (void *)(j));
        if (status != 0)
            printf("last_created_thread = %d :: j = %d\n", last_created_thread, j);
            fflush(stdout);
            break;
        else
            last_created_thread = j;
    for (j = 0; j <= last_created_thread; j++)
        pthread_join(thr_hp[j], NULL);
/* ========================================================================= */
/* -- EXTERNAL FUNCTIONS --------------------------------------------------- */
/* ========================================================================= */
int
main (int argc, char **argv)
    int num_threads = 0;
    printf("Threading Library Comparison Test\n");
    if (argc != 2)
        printf("Usage: %s n\n  where n is no. of threads\n", argv[0]);
        exit(1);
    num_threads = atoi(argv[1]);
    if ((num_threads < 1) || (num_threads > MAX_THREADS))
        printf("The no of thread should between 1 and %u.\n", MAX_THREADS);
        exit(1);
    /* Launch POSIX Threads */
    create_threads_pth(num_threads);
    /* Launch OCI Threads */
    create_threads_oci(num_threads);
    return 0;
}