problem with locks on head, backend crash

Hello

when I tested ptop, I found some problems

this pgbench is very slow and when after getting table of locks from
ptop I got backend crash.

[pavel(at)prg31 ~]$ /usr/local/pgsql/bin/pgbench -c80 -t1000 postgres
starting vacuum...end.
WARNING: you don't own a lock of type ShareLock
WARNING: you don't own a lock of type ShareLock
WARNING: terminating connection because of crash of another server process
DETAIL: The postmaster has commanded this server process to roll back
the current transaction and exit, because another server process
exited abnormally and possibly corrupted shared memory.
HINT: In a moment you should be able to reconnect to the database and
repeat your command.
WARNING: terminating connection because of crash of another server process
DETAIL: The postmaster has commanded this server process to roll back
the current transaction and exit, because another server process
exited abnormally and possibly corrupted shared memory.

from log:

LOG: unexpected EOF on client connection
LOG: could not send data to client: Přerušena roura (SIGPIPE)
LOG: unexpected EOF on client connection
LOG: could not send data to client: Přerušena roura (SIGPIPE)
LOG: unexpected EOF on client connection
WARNING: problem in alloc set MessageContext: req size > alloc size
for chunk 0x8b6d1e0 in block 0x8b6bb50
WARNING: problem in alloc set MessageContext: req size > alloc size
for chunk 0x8b6d1e0 in block 0x8b6bb50
LOG: server process (PID 29693) was terminated by signal 11: Segmentation fault
LOG: terminating any other active server processes
WARNING: terminating connection because of crash of another server process
DETAIL: The postmaster has commanded this server process to roll back
the current transaction and exit, because another s
HINT: In a moment you should be able to reconnect to the database and
repeat your command.
WARNING: terminating connection because of crash of another server process

Regards
Pavel Stehule