The following bug has been logged online:

Bug reference: 2502
Logged by: J. R. Fisher
Email address: psql (AT) jeffryfisher (DOT) net
PostgreSQL version: 8.1
Operating system: Linux
Description: PQclear: "invalid next size"
Details:

One patch of C++, two programs using it. One program runs without a hitch,
the other always explodes. In the debugger, this is what's executing:

result = PQexec (conn->handle, cmd);// char* cmd= "BEGIN"
if (PQresultStatus (result) != PGRES_COMMAND_OK) {
... // skipped because result *is* OK
}
if (!savingCursor) {
PQclear (result); // blows up here, but only in one program, not the
others

*** glibc detected *** free(): invalid next size (normal): 0x08068ab0

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"J. R. Fisher" <psql (AT) jeffryfisher (DOT) net> writes:
Sounds like a memory clobber. The odds are extremely high that the
clobber is in your own code, not libpq. If nothing else comes to mind,
you could probably use ElectricFence or some other debugging-malloc
package to help find the problem.

regards, tom lane

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