Assert error/hangs running the performance sample code

Question

Hi,
I'm doing some work to understand how fast I can expect Berkeley DB to run and I found the 2006 white paper on [Performance Metrics and Benchmarks|http://www.oracle.com/technology/products/berkeley-db/pdf/berkeley-db-perf.pdf] so I downloaded the [sample code|http://www.oracle.com/technology/products/berkeley-db/files/perf.zip] and made a couple of fixes to make it run with 4.7.25 (shown at the end).
When I run 'make test' it frequently hangs on the "Transactional Data Store (write, in-memory logging)" test under OS X 10.5.7 and under Debian lenny (kernel 2.6.26-1-amd64).
If I rebuild BDB with --enable-diagnostic I get this assertion error.
jmeredith@op:~/src/perf$ rm -rf TESTDIR ; ./t
Using Berkeley DB 4.7.25 - ops: 1000000; keysize: 8; datasize: 32
Data Store (read):
elapsed time: 0.392573 seconds : 2.5473e+06 key/data pairs per sec
Data Store (bulk read):
elapsed time: 1.615233 seconds : 2.66339e+07 key/data pairs per sec
Data Store (write):
elapsed time: 0.629771 seconds : 1.58788e+06 key/data pairs per sec
Transactional Data Store (read):
elapsed time: 2.413665 seconds : 414308 key/data pairs per sec
assert failure: ../dist/../txn/txn_region.c/451: "td->mvcc_ref > 0"
[0x4f431d]
[0x4f41a9]
[0x44cdff]
[0x4f2e1e]
[0x42f0d3]
[0x4f3faf]
[0x4fddee]
[0x4f8dde]
[0x4d975c]
[0x4c9991]
[0x4e417d]
[0x40137c]
[0x40198e]
[0x52613b]
[0x4001b9]
Aborted (core dumped)
Here are the changes to get the code to build.
--- perf/t.c 2006-06-28 17:15:47.000000000 -0600
+++ perf-fixed/t.c 2009-07-06 09:44:43.000000000 -0600
@@ -1,4 +1,5 @@
#include <sys/types.h>
+#include <sys/time.h>
#include <stdio.h>
#include <stdlib.h>
@@ -38,7 +39,15 @@
char *progname;
-extern void __os_clock(DB_ENV *, u_int32_t *, u_int32_t *);
+void
+__os_clock(DB_ENV e, u_int32_t secs_ptr, u_int32_t *usecs_ptr)
+{
+ struct timeval t;
+
+ gettimeofday(&t, NULL);
+ *secs_ptr = (u_int32_t) t.tv_sec;
+ *usecs_ptr = (u_int32_t) t.tv_usec;
+}
void cleanup(void);
void op_ds(u_int, int);
@@ -364,7 +373,7 @@
op_tds(ops, 0, 0);
res("Transactional Data Store (read):", ops);
- op_tds(ops, 1, DB_LOG_INMEMORY);
+ op_tds(ops, 1, DB_LOG_IN_MEMORY);
res("Transactional Data Store (write, in-memory logging):", ops);
op_tds(ops, 1, DB_TXN_NOSYNC);

Answer 1

Hi,
I reproduced your problem on Ubuntu 4.2.3 with db 4.7.25 and saw the same assert error as you. From the error message, the program asserts error/hangs at the "Transactional Data Store (write, in-memory logging)", that is calling op_tds() with DB_LOG_IN_MEMORY as the flags.
The problem comes from your change on the sample code that the DB_LOG_IN_MEMORY is set with wrong API. The DB_LOG_IN_MEMORY should be set in DB_ENV->log_set_config(). Please refer to [DB_ENV->log_set_config|http://www.oracle.com/technology/documentation/berkeley-db/db/api_c/env_log_set_config.html] and its flag DB_LOG_IN_MEMORY.
I change env's setting flags in op_tds() as follows. In this way, the error I saw is eliminated and the program works as expected.
The original code is:
PERF_CHECK(
        dbenv->set_flags(dbenv, DB_AUTO_COMMIT | txn_flags, 1) == 0);"
{code}
I change it to:
{code}
if (txn_flags == DB_LOG_IN_MEMORY) {
        PERF_CHECK(
           dbenv->log_set_config(dbenv, DB_LOG_IN_MEMORY, 1) == 0);
        txn_flags = 0;
PERF_CHECK(
        dbenv->set_flags(dbenv, DB_AUTO_COMMIT | txn_flags, 1) == 0);
{code}
Please apply the change and l*et us know if it works on your machine.
Regards,
Emily Fu, Oracle Berkeley DB