BUG #6249: Segmentation fault in VirtualXactLock()

The following bug has been logged online:

Bug reference: 6249
Logged by: Fujii Masao
Email address: masao(dot)fujii(at)gmail(dot)com
PostgreSQL version: 9.2dev
Operating system: Linux hermes 2.6.38-11-generic #50-Ubuntu SMP Mon Sep 12
21:18:14 UTC 2011 i686 i686 i386 GNU/Linux
Description: Segmentation fault in VirtualXactLock()
Details:

When I built Streaming Replication and Hot Standby environment, set
max_standby_streaming_delay to 1s and ran the following shell script which
creates the conflict between read-only query and recovery, SEGV occurred on
the standby.

----------------------
#!/bin/sh

# Master's port: 5432
# Standby's port: 9999

psql -c "CREATE TABLE tbl (id int)" -p 5432
psql -c "INSERT INTO tbl VALUES(1)" -p 5432

sleep 1

psql -c "SELECT pg_sleep(60) FROM tbl" -p 9999 &

sleep 1

psql -c "DELETE FROM tbl" -p 5432
psql -c "VACUUM tbl" -p 5432
----------------------

backtrace is:
Core was generated by `postgres: startup process recovering 000000'.
Program terminated with signal 11, Segmentation fault.
#0 0x083114db in VirtualXactLock ()
(gdb) bt
#0 0x083114db in VirtualXactLock ()
#1 0x083072d1 in ResolveRecoveryConflictWithVirtualXIDs ()
#2 0x08307355 in ResolveRecoveryConflictWithSnapshot ()
#3 0x080b8abc in heap_xlog_clean ()
#4 0x080bc31a in heap2_redo ()
#5 0x080f02fd in StartupXLOG ()
#6 0x080f6c70 in StartupProcessMain ()
#7 0x0811d5f9 in AuxiliaryProcessMain ()
#8 0x082d17e4 in StartChildProcess ()
#9 0x082cd151 in PostmasterMain ()
#10 0x0824d6b4 in main ()

I was not able to reproduce this issue on 9.1.1. So the bug would exist only
on 9.2dev.