[Varnish] #543: vcl.discard causes crash

[Varnish]

#543: vcl.discard causes crash
----------------------+-----------------------------------------------------
 Reporter:  sky       |        Owner:  phk  
     Type:  defect    |       Status:  new  
 Priority:  normal    |    Milestone:       
Component:  varnishd  |      Version:  trunk
 Severity:  normal    |   Resolution:       
 Keywords:            |  
----------------------+-----------------------------------------------------
Comment (by janne):

 I'm seeing similar problem with 2.0.4 under very high load of cache misses
 with rather small cache file size. I have not checked the code, but to me
 it seems cache-cleaner thread dies when it's unable to discard items from
 the cache fast enough to meet the requirements for new space. This problem
 can be reproduced quite easily with a 100M cache size, few hundred cache
 missing requests per second with for example 1Mb file size.

 /usr/sbin/varnishd -P /var/run/varnish.pid -a :80 :81 -f
 /etc/varnish/default.vcl -T 127.0.0.1:6082 -t 120 -w 50,2000,120 -u
 varnish -g varnish -s file,/opt/varnish/varnish_storage.bin,100M

 This test setup / configuration does not make much sense, but it's still
 annoying to see varnish constantly dying.

 Child (23899) died signal=6
 Child (23899) Panic message: Assert error in STV_alloc(), stevedore.c line
 71: Condition((st) != NULL) not true.  thread = (cache-worker) sp =
 0x2aaab186e008 {   fd = 32, id = 32, xid = 1876476933, client =
 10.0.1.88:11419,   step = STP_FETCH,   handling = discard, ws =
 0x2aaab186e078 { id = "sess",     {s,f,r,e} =
 {0x2aaab186e808,,+385,(nil),+16384},   }, worker = 0x7b258bc0 {     },
 vcl ={       srcname = {"input",         "Default", },     },   obj =
 0x2aaaab100000 {     refcnt = 1, xid = 1876476933,ws = 0x2aaaab100028 {
 id = "obj",       {s,f,r,e} ={0x2aaaab100358,,+239,(nil)+7336},},     http
 = {       ws = 0x2aaaab100028 {          id = "obj", {s,f,r,e} =
 {0x2aaaab100358,,+239,(nil),+7336},       }

 Os: Linux

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Ticket URL: <http://varnish.projects.linpro.no/ticket/543#comment:2>
Varnish <http://varnish.projects.linpro.no/>
The Varnish HTTP Accelerator