[Vm-dev] Image freeze because handleTimerEvent and Seaside process gone?!

Adrian Lienhard adi at netstyle.ch
Mon Dec 6 10:55:55 UTC 2010

Hi all,

We've been experiencing an "interesting" problem: the image freezes and does not response to HTTP requests anymore after it has been running for days. 

Here some basic information about our setup:

Squeak VM 4.0.3-2202 compiled with gcc 4.3.2
PharoCore 1.1
OS Debian Lenny amd64 (CPUs are 4 Intel Xeon E5530 2.40GHz)

- We have never seen the problem with the Squeak VM 3.9-9 and Squeak 3.9 on the identical machine and with the same application source (modulo some adaptations to make it run on Pharo).
- We run the VM with -mmap 512m -vm-sound-null -vm-display-null, and the UI process is suspended (Project uiProcess suspend)
- VM does not hog the CPU and memory usage is normal
- The meantime between failure is several weeks and we haven't managed to reproduce the problem
- The application mainly serves HTTP requests. When the image does not receive requests for some time we send it a STOP signal, when a request comes in it is sent a CONT signal.
- lsof shows
	TCP *:9093 (LISTEN)
	TCP server:9093->server:46930 (CLOSE_WAIT)

Below is a GDB backtrace and the Smalltalk stacks from an image that was frozen (the VM had been running for almost 100 hours):

(gdb) bt
#0  0x08072020 in ?? ()
#1  <signal handler called>
#2  0xb766f5e0 in malloc () from /lib/libc.so.6
#3  <function called from gdb>
#4  0xb76c50c8 in select () from /lib/libc.so.6
#5  0x08071063 in aioPoll ()
#6  0xb778bb8d in ?? () from /usr/lib/squeak/4.0.3-2202//so.vm-display-null
#7  0x000003e8 in ?? ()
#8  0x997b5a34 in ?? ()
#9  0xbfe7cb28 in ?? ()
#10 0x08074575 in ioRelinquishProcessorForMicroseconds ()
Backtrace stopped: frame did not save the PC

(gdb) call printCallStack() 
-1719969228 >idleProcess
-1719969320 >startUp
-1740134028 BlockClosure>newProcess
$3 = -1755344892

(gdb) call (int) printAllStacks()
-1719969228 >idleProcess
-1719969320 >startUp
-1740134028 BlockClosure>newProcess

-1740113860 >finalizationProcess
-1740113952 >restartFinalizationProcess
-1740113532 BlockClosure>newProcess

-1740134424 SmalltalkImage>lowSpaceWatcher
-1740134516 SmalltalkImage>installLowSpaceWatcher
-1740134300 BlockClosure>newProcess

-1719451488 Delay>wait
-1719451580 BlockClosure>ifCurtailed:
-1719451704 Delay>wait
-1719451796 InputEventPollingFetcher>waitForInput
-1740126940 InputEventFetcher>eventLoop
-1740127032 InputEventFetcher>installEventLoop
-1740126816 BlockClosure>newProcess

-1719557780 UnixOSProcessAccessor>grimReaperProcess
-1740113624 BlockClosure>repeat
-1740113716 UnixOSProcessAccessor>grimReaperProcess
-1740117340 BlockClosure>newProcess

[omitted many newlines between output above]

What is striking from the above process listing is that two processes are missing: the handleTimerEvent process and the Seaside process (that is, the TCP listener loop). How comes these processes vanished?

This may be related to Pharo or to the Squeak VM.

Has anybody else seen this problem? Any idea how to debug/fix this issue is very much appreciated!


CCed to pharo-dev since this may be related to Pharo; please respond on the squeak-vm list

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