Re: memory leak in libpq , definitely lost: 200 bytes in 1 blocks, indirectly lost: 2,048 bytes in 1 blocks ...

Heikki Linnakangas <hlinnaka(at)iki(dot)fi> writes:
> On 10/10/2016 12:38 PM, Simplex wrote:
>> } Repeat several times to get the leak

> I was not able to reproduce this.

I was able to reproduce it, or at least something that looks similar,
after a good deal of fooling around. I needed:

* SSL turned on
* server recovering from crash, so that it rejects at least one connection
attempt with "the database system is starting up"

This causes the successful PQreset call to leave an async result behind
containing the earlier connection rejection message. That might or might
not be a logic bug in PQreset, but it doesn't really seem all that wrong.
But then the PQexec calls PQsendQueryStart which cavalierly resets
conn->result to NULL, leaking the async result. I fixed PQsendQueryStart
to use pqClearAsyncResult which is less cavalier, and then I couldn't
reproduce the leak anymore.

Interestingly, I couldn't make it happen (ie get to PQsendQueryStart with
a non-null result) without valgrind active on the client --- so there's
some timing considerations involved too, apparently.

regards, tom lane