[Mongrel] Mongrel hangs in production. gdb stack included

Erik Morton eimorton at gmail.com
Wed Apr 30 09:28:34 EDT 2008


It happens at night usually so I haven't had a chance to run show  
innodb status yet. I will say that once when it happened show  
processlist still showed all of the expected connections.

I have no large hooks. Just a call to MyObject.find(:all, :include  
=> :parent) that generates an SQL statement approximately 2,000-3,000  
characters long. My max_packet is set to 16mb

Erik
On Apr 30, 2008, at 8:50 AM, Dave Cheney wrote:
> What does
> mysql> show innodb status\G
> mysql> show processlist;
>
> show during the hang, it may be a deadlock in the db. We had similar  
> problems with large after_save hooks that would deadlock updating  
> multiple tables.
>
> Cheers
>
> Dave
>
> On 30/04/2008, at 12:31 PM, Erik Morton wrote:
>
>> I am getting hanging Mongrels daily under light volume.
>>
>> Mongrel Web Server 1.1.4
>> Apache 2.2 w/mod_proxy
>> RedHat EL4 2.6.9-5.ELsmp #1 SMP Wed Jan 5 19:30:39 EST 2005 i686  
>> i686 i386 GNU/Linux
>> ruby 1.8.5 (2006-08-25) [i686-linux]
>> fastthread (1.0.1)
>> Mysql 5.0.45
>>
>> The mongrels are hanging with 0% CPU, their database connections  
>> are still being reported as open by mysql. Attaching gdb to the  
>> processes yields similar results (included below). I have no idea  
>> about what the next steps are in figuring out what is going on --  
>> short of upgrading to ruby 1.8.6!
>>
>> Help and pointers are much appreciated.
>>
>> (gdb) whe
>> #0  0x0058b7a2 in _dl_sysinfo_int80 () from /lib/ld-linux.so.2
>> #1  0x0065ec93 in __read_nocancel () from /lib/tls/libc.so.6
>> #2  0x04ccc27f in vio_read (vio=0xfffffe00, buf=0xfffffe00 <Address  
>> 0xfffffe00 out of bounds>, size=-512) at viosocket.c:44
>> #3  0x04ccc356 in vio_read_buff (vio=0x9088ae0,
>>   buf=0xb5d471df "e Travel Plaza, located on I-90 eastbound between  
>> Interchanges 48A (Pembroke) and 48 (Batavia), at milepost 397. The  
>> renovation projects scheduled at Ulster and Pembroke travel plazas,  
>> in addition to "..., size=4412) at viosocket.c:95
>> #4  0x04ccd8f6 in my_real_read (net=0x913eb10, complen=0xbfed5e98)  
>> at net.c:804
>> #5  0x04ccdc30 in my_net_read (net=0x913eb10) at net.c:978
>> #6  0x04cc6b78 in net_safe_read (mysql=0x913eb10) at client.c:596
>> #7  0x04cc792f in cli_read_rows (mysql=0x913eb10,  
>> mysql_fields=0xad6e1a0, fields=59) at client.c:1343
>> #8  0x04cc9881 in mysql_store_result (mysql=0x913eb10) at client.c: 
>> 2697
>> #9  0x04ca299f in store_result (obj=3076071240) at mysql.c:677
>> #10 0x0805bcb4 in rb_call0 (klass=3076091220, recv=3076071240,  
>> id=27825, oid=4294966784, argc=1, argv=0xbfed6160, body=0xb7596458,  
>> flags=0) at eval.c:5665
>> #11 0x0805c017 in rb_call (klass=3076091220, recv=3076071240,  
>> mid=27825, argc=1, argv=0xbfed6160, scope=0) at eval.c:6048
>> #12 0x08058127 in rb_eval (self=3076059900, n=0x113c) at ruby.h:654
>> #13 0x0805d99b in rb_yield_0 (val=6, self=3076059900, klass=0,  
>> flags=0, avalue=0) at eval.c:4987
>> #14 0x08058475 in rb_eval (self=3076059900, n=0x113c) at eval.c:3248
>> #15 0x08058952 in rb_eval (self=3076059900, n=0x113c) at eval.c:3624
>> #16 0x0805d99b in rb_yield_0 (val=6, self=3076059900, klass=0,  
>> flags=0, avalue=0) at eval.c:4987
>> #17 0x08058475 in rb_eval (self=3082341360, n=0x113c) at eval.c:3248
>> #18 0x0805b9ce in rb_call0 (klass=3082341260, recv=3082341360,  
>> id=53385, oid=4294966784, argc=0, argv=0x0, body=0xb7b931f8,  
>> flags=0) at eval.c:5954
>> #19 0x0805c017 in rb_call (klass=3082341260, recv=3082341360,  
>> mid=53385, argc=0, argv=0x0, scope=0) at eval.c:6048
>> #20 0x08058127 in rb_eval (self=3082341360, n=0x113c) at ruby.h:654
>>
>>
>> (gdb) whe
>> #0  0x0058b7a2 in _dl_sysinfo_int80 () from /lib/ld-linux.so.2
>> #1  0x0065ec93 in __read_nocancel () from /lib/tls/libc.so.6
>> #2  0x01d6d27f in vio_read (vio=0xfffffe00, buf=0xfffffe00 <Address  
>> 0xfffffe00 out of bounds>, size=-512) at viosocket.c:44
>> #3  0x01d6d356 in vio_read_buff (vio=0x93e7c30,
>>   buf=0xb6f00db4 "~\202\215^-?\213\201?QJ\237\203\201\230D?\232V 
>> \201M8\233\224?\201\021-o\217[\200?#?\211\236\200?\203??0\213\021wC? 
>> h\211\236j\234?\215\210F]̣\232\207\006Q\b\236\220\205?Dv\231t\204? 
>> 8\220\224 \203?-\214\216\236\202?$\026\210?\201?\203Y?u\221?v??? 
>> \217?jS??\215?]\206??\213?P?\235?\212\023DS\230?\210 at 8\210\223d 
>> \206o-?\215?\204?$R\210z\202?\203\017??\230\236v??\026\226",  
>> size=503704)
>>   at viosocket.c:95
>> #4  0x01d6e8f6 in my_real_read (net=0x93e71a8, complen=0xbff9efa8)  
>> at net.c:804
>> #5  0x01d6ec30 in my_net_read (net=0x93e71a8) at net.c:978
>> #6  0x01d67b78 in net_safe_read (mysql=0x93e71a8) at client.c:596
>> #7  0x01d6892f in cli_read_rows (mysql=0x93e71a8,  
>> mysql_fields=0xaec8f00, fields=51) at client.c:1343
>> #8  0x01d6a881 in mysql_store_result (mysql=0x93e71a8) at client.c: 
>> 2697
>> #9  0x01d4399f in store_result (obj=3071130920) at mysql.c:677
>> #10 0x0805bcb4 in rb_call0 (klass=3071150400, recv=3071130920,  
>> id=27825, oid=4294966784, argc=1, argv=0xbff9f270, body=0xb70e0058,  
>> flags=0) at eval.c:5665
>> #11 0x0805c017 in rb_call (klass=3071150400, recv=3071130920,  
>> mid=27825, argc=1, argv=0xbff9f270, scope=0) at eval.c:6048
>> #12 0x08058127 in rb_eval (self=3071126200, n=0x7af98) at ruby.h:654
>>
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