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From Ben Ricker <bric...@us-rx.com>
Subject Re: runaway threads eating cpu cycles on Solaris 7
Date Thu, 15 Feb 2001 21:31:19 GMT
This sounds like garbage collection by the JVM. I know there is a way to
control when the JVM garbage collects, but I amnot sure how. Anybody
else know how to do that?

Ben Ricker
Senior System Administrator
US-Rx, Inc.


On 15 Feb 2001 15:43:22 -0500, Kelly Kleinfelder wrote:
> We are running Tomcat 3.2.1 and Solaris 7 on a Sun e250 with 4 400Mhz processors. The
problem we're having is that one thread is chewing up the majority of the cpu cycles and sometimes
causes tomcat to hang.
> 
> I have included sample mpstat data and the output from ps -L -p PID:
> 
> ps -L -p 26361
>    PID   LWP TTY     LTIME CMD
>  26361     1 ?        0:03 java
>  26361    22 ?        1:02 java
>  26361    23 ?       40:57 java
>  26361    24 ?        1:43 java
>  26361    26 ?        0:09 java
>  26361    67 ?        0:03 java
>  (24 entries deleted for brevity. All were at 0:00 LTIME)
> 
> mpstat 30
> CPU minf mjf xcal  intr ithr  csw icsw migr smtx  srw syscl  usr sys  wt idl
>   0   12   0   12     6    4   17    0    1    0    0    75    0   3   1  96
>   1    6   0    6     4    1   14    3    0    0    0    52   59   1   1  39
>   2    0   0    0    64   62   12    2    0    0    0    20   41   1   1  57
>   3    4   0   14   203    3   27    0    1    0    0    26    0   0   0 100
> CPU minf mjf xcal  intr ithr  csw icsw migr smtx  srw syscl  usr sys  wt idl
>   0    0   0    1     3    2   16    0    1    1    0    51    1   3   1  95
>   1    0   0    0     5    1    6    4    0    0    0     3   81   0   0  19
>   2    0   0    2    19   19   17    0    1    0    0    16    0   0   0 100
>   3    4   0   13   202    2   15    1    1    0    0    41   19   2   0  78
> CPU minf mjf xcal  intr ithr  csw icsw migr smtx  srw syscl  usr sys  wt idl
>   0    4   0    5     5    5   17    0    1    1    0    70    1   2   1  96
>   1    4   0    0     5    1   11    4    0    0    0    36   84   0   0  15
>   2    2   0    4    26   26   28    0    1    0    0    81    2   0   0  98
>   3    0   0   20   204    4   19    1    0    0    0    24   14   0   0  86
> 
> Before today, this was happening about every 3 days. Today it happened 5 hours apart.
By going through our logs, we have determined that this is not caused by any specific user
action. It is also not caused by server load, as it mostly happens with less than 5 users
accessing the application. It is also not a gradual thing. Our sar statistics show that our
processor idle time is 98% and then 5 minutes later it's down to 83% and in another 5 minutes,
it's at 49%.
> 
> Is there any way that I can tell exactly what is happening in the offending thread?
> 
> Any other ideas on what's causing this problem?
> 
> Thanks,
> Kelly


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