[unixODBC-support] Memory leak in SQLFetch?

Craddock, Richard C cmi5 at cdc.gov
Tue Dec 14 17:14:57 GMT 2004


Here is the latest information that I have discovered.

In order to detect memory leaks I run free -b before and after executing
my code.  I assume that the difference between the two was allocated but
not freed by the application.

If I execute the SQLfetch() loop 101 times I get the following data:

[root at localhost file_upload]# free -b
             total       used       free     shared    buffers
cached
Mem:    1326329856  604139520  722190336          0  281374720
231182336
-/+ buffers/cache:   91582464 1234747392
Swap:   4104372224          0 4104372224
[root at localhost file_upload]# ./testfetch
[root at localhost file_upload]# free -b
             total       used       free     shared    buffers
cached
Mem:    1326329856  604270592  722059264          0  281391104
231198720
-/+ buffers/cache:   91680768 1234649088
Swap:   4104372224          0 4104372224

This shows a reproducible difference of 131072 bytes between runs.

If I allow the SQLfetch() loop execute 11 times I get the following:

[root at localhost file_upload]# free -b
             total       used       free     shared    buffers
cached
Mem:    1326329856  604532736  721797120          0  281628672
231239680
-/+ buffers/cache:   91664384 1234665472
Swap:   4104372224          0 4104372224
[root at localhost file_upload]# ./testfetch
[root at localhost file_upload]# free -b
             total       used       free     shared    buffers
cached
Mem:    1326329856  604532736  721797120          0  281636864
231243776
-/+ buffers/cache:   91652096 1234677760
Swap:   4104372224          0 4104372224

There is no difference between the two.  Maybe there is a memory
corruption involved?  Attached is the sql.log file for the 100 run case.

Thanks,
Cameron

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