Comment #3 on issue 99 by thomchin: Memcached 1.4.2 server segmentation
fault
http://code.google.com/p/memcached/issues/detail?id=99
Thanks for taking a look at this. The sample code that I provided (testing
how
libevent behaves in regards to event.ev_base) seems to indicate that
event.ev_base is
never altered by event_base_set().
Let me know which version of memcached you want me to build and if
attaching the
subsequent core file to this thread is the preferred means of getting the
file to
you. I had to reload the test script in rapid succession several times to
cause it
to fault because it has to encounter a state where writing will block.
Here is a
quick snapshot of what happened:
<31 new auto-negotiating client connection
31: going from conn_new_cmd to conn_waiting
31: going from conn_waiting to conn_read
31: going from conn_read to conn_parse_cmd
31: Client using the ascii protocol
<31 set test 0 10 50526
31: going from conn_parse_cmd to conn_nread
FOUND KEY test
31 STORED
31: going from conn_nread to conn_write
31: going from conn_write to conn_new_cmd
31: going from conn_new_cmd to conn_waiting
31: going from conn_waiting to conn_read
31: going from conn_read to conn_closing
<31 connection closed.
<31 new auto-negotiating client connection
31: going from conn_new_cmd to conn_waiting
31: going from conn_waiting to conn_read
31: going from conn_read to conn_parse_cmd
31: Client using the ascii protocol
<31 get test
FOUND KEY test
31 sending key test
31 END
31: going from conn_parse_cmd to conn_mwrite
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0xb65b9b90 (LWP 32183)]
0xb7f8f436 in event_add () from /usr/lib/libevent-1.4.so.2
(gdb) backtrace
#0 0xb7f8f436 in event_add () from /usr/lib/libevent-1.4.so.2
#1 0x5ff40000 in ?? ()
#2 0x0000b7f8 in ?? ()
#3 0x080e4b38 in ?? ()
#4 0x080e9260 in ?? ()
#5 0xb7f7843e in pthread_mutex_lock () from /lib/libpthread.so.0
#6 0xc35d5f5e in ?? ()
#7 0xffffffb8 in ?? ()
#8 0x1cc483ff in ?? ()
#9 0x5d5f5e5b in ?? ()
#10 0x85838dc3 in ?? ()
...
#265 0x02fe8344 in ?? ()
#266 0x07c7ba75 in ?? ()
#267 0x00000000 in ?? ()
(gdb) gcore
Saved corefile core.32177
gdb ./memcached-debug core.32177
GNU gdb 6.8
Copyright (C) 2008 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later
<http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "i686-pc-linux-gnu"...
Core was generated by `/home/thom/memcached-1.4.2/memcached-debug -l
localhost -vvv'.
Program terminated with signal 11, Segmentation fault.
[New process 32184]
[New process 32183]
[New process 32182]
[New process 32181]
[New process 32180]
[New process 32177]
#0 0xffffe410 in __kernel_vsyscall ()
(gdb) backtrace
#0 0xffffe410 in __kernel_vsyscall ()
#1 0xb7f7a8c5 in ?? ()
#2 0x00000000 in ?? ()
(gdb)
Hope this helps.
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