[hunchentoot-devel] Server sporadically hanging

[Jeff Cunningham]

Zach Beane wrote:
> On Wed, Feb 20, 2008 at 08:09:18AM -0800, Jeff Cunningham wrote:
>   
>> I am having a problem that I can't replicate on demand but has been 
>> happening with increasing frequency. I am hoping some of you might 
>> suggest ways to troubleshoot it. I don't know that it is a Hunchentoot 
>> problem, per se, but it may be an interaction problem between 
>> Hunchentoot and Apache2 via mod_lisp2.
>>
>> The symptom is the server is hung first thing in the morning when I 
>> check it. The cpu is at 99% activity on the server image (sbcl). When I 
>> look in the error_log I see dozens of these:
>>     
> [snip]
>
> I had trouble like this in the past, and so far in every case it was
> due to me making a mistake in the handler and going into an infinite
> loop. I don't know if that's the case for you, but I had good luck
> debugging it by adding extra info to thread names so I could identify
> handlers that might be stuck.
>
> http://xach.livejournal.com/132391.html has a writeup.
>
> You can also troubleshoot by interrupting all threads and requesting
> their backtrace (best to write it to a file or save them to a table or
> something like that). That can also help identify problems.
>
> Zach
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>
>
>   
Thanks, Zach. I just tried the following:

(mapcar (lambda (thread)
        (sb-thread:interrupt-thread thread
                            (lambda ()
                            (throw 'hunchentoot::handler-done
                              ""))))
        (sb-thread:list-all-threads))

And it says it can't find the tag 'hunchentoot::handler-done (I assume). 
Yet, it shows up in the list of package symbols, exported even:

attempt to THROW to a tag that does not exist: HANDLER-DONE
   [Condition of type SB-INT:SIMPLE-CONTROL-ERROR]

Restarts:
 0: [ABORT] Abort SLIME compilation.
 1: [ABORT] Return to SLIME's top level.
 2: [TERMINATE-THREAD] Terminate this thread (#<THREAD "worker" {D813B61}>)

Backtrace:
  0: ("no debug information for frame")
  1: ((LAMBDA NIL))
  2: (SB-THREAD:INTERRUPT-THREAD #<SB-THREAD:THREAD "worker" {D813B61}> 
#<FUNCTION (LAMBDA NIL) {D84CC55}>)
  3: (SB-IMPL::MAP1 #<FUNCTION (LAMBDA (THREAD)) {D84CF95}> 
((#<SB-THREAD:THREAD "worker" {D813B61}> #<SB-THREAD:THREAD 
"hunchentoot-worker-34" {D7CB2D1}> #<SB-THREAD:THREAD 
"hunchentoot-worker-33" {D7D92B9}> #<SB-THREAD:THREAD 
"hunchentoot-worker-32" {D777351}> #<SB-THREAD:THREAD 
"hunchentoot-worker-31" {DA38F11}> #<SB-THREAD:THREAD 
"hunchentoot-worker-30" {DC5A989}> ...)) :LIST T)
  4: (MAPCAR #<FUNCTION (LAMBDA (THREAD)) {D84CF95}> (#<SB-THREAD:THREAD 
"worker" {D813B61}> #<SB-THREAD:THREAD "hunchentoot-worker-34" 
{D7CB2D1}> #<SB-THREAD:THREAD "hunchentoot-worker-33" {D7D92B9}> 
#<SB-THREAD:THREAD "hunchentoot-worker-32" {D777351}> #<SB-THREAD:THREAD 
"hunchentoot-worker-31" {DA38F11}> #<SB-THREAD:THREAD 
"hunchentoot-worker-30" {DC5A989}> ...))

--Jeff