On Wed, Aug 12, 2009 at 11:16 AM, [email protected]<[email protected]> wrote: > Bart Van Assche wrote: > > On Thu, Aug 6, 2009 at 12:02 PM, > >> Any opinions of whether this error could be causing my glibc double free > >> errors, or whether it is a red-herring? > > > > It is unlikely that the above message printed by Valgrind is related > > to the double free reported by glibc. > > > > Try to trigger as much code as you can in your application and in > > Net-SNMP and see whether this makes Valgrind report more errors. > > I left valgrind running for over 20 hours with the application doing > some simple snmpget-ing. After 8.5 hours and 29,664 SNMP gets - I got > the first valgrind errors - which were all from a single call to > snmp_free_pdu with a pdu that had already been freed after a > snmp_synch_response returned a STAT_ERROR. No other valgrind errors were > received. > > Normally the application would crash, but it seems valgrind allows it to > continue - and the application ran for another 9 hours 22 minutes, and > 32,767 SNMP gets with no valgrind errors, and then I got the same > valgrind errors complaining that the pdu had already been freed. The > only valgrind errors I could find where as a direct result of memory > being freed twice.
The behavior of the malloc() and free() replacements implemented in Valgrind's memcheck is slightly different of the glibc versions: while the free() function implemented in glibc frees memory immediately, Valgrind delays freeing memory (see also the documentation of the command-line parameter --freelist-vol). Can you please create a bug report with the information you posted on the Net-SNMP coders mailing list, and also the messages printed by Valgrind, including the "Address ... is ... bytes inside a block of size ... alloc'd" information ? See also https://sourceforge.net/tracker/?group_id=12694&atid=112694. Bart. ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ Net-snmp-coders mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/net-snmp-coders
