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Posted to users@tomcat.apache.org by to...@r322.com on 2011/05/24 04:45:45 UTC
Tomcat latency
Hello:
I have a problem where a simple wget call to docs/config/valve.html can
sometimes take up to 15 seconds to process.
I have a script that does a wget call to valve.html every 5 seconds.
Most of the time it's fast. However, today in the past 6 hours I had 13
cases where it took over 3 seconds for wget to return valve.html. This
is happening across 7 servers pretty consistently and I can't figure out
why. Any suggestions to help me narrow down the problem?
I'm going to modify the script to check disk i/o and load when the
problem happens. Normally these numbers are sane with upwards of ~60%
disk utilization load of ~2.
Dual processor Intel(R) Xeon(R) CPU X5680 @ 3.33GHz.
The stats right now.
top - 22:42:34 up 26 days, 7:17, 1 user, load average: 1.64, 1.31,
1.03
Tasks: 115 total, 1 running, 114 sleeping, 0 stopped, 0 zombie
Cpu(s): 11.7%us, 1.1%sy, 0.0%ni, 56.3%id, 30.7%wa, 0.0%hi, 0.2%si,
0.0%st
Mem: 8197432k total, 8146536k used, 50896k free, 3212k
buffers
Swap: 18723708k total, 397296k used, 18326412k free, 683448k cached
iostat -xd
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s
avgrq-sz avgqu-sz await svctm %util
sda 4.22 29.23 77.11 1.75 1833.10 247.79
26.39 1.04 13.16 5.60 44.20
sdb 0.00 0.00 0.00 0.00 0.00 0.00
39.37 0.00 2.83 2.39 0.00
Ubuntu 9.10
/opt/tomcat6/bin/version.sh
Using CATALINA_BASE: /opt/tomcat6
Using CATALINA_HOME: /opt/tomcat6
Using CATALINA_TMPDIR: /opt/tomcat6/temp
Using JRE_HOME: /usr/lib/jvm/java-6-sun/jre
Server version: Apache Tomcat/6.0.20
Server built: May 14 2009 01:13:50
Server number: 6.0.20.0
OS Name: Linux
OS Version: 2.6.31-14-server
Architecture: amd64
JVM Version: 1.6.0_22-b04
JVM Vendor: Sun Microsystems Inc.
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RE: Tomcat latency
Posted by David Dabbs <dm...@gmail.com>.
> -----Original Message-----
> From: David kerber [mailto:dckerber@verizon.net]
> Sent: Thursday, May 26, 2011 9:33 AM
> To: Tomcat Users List
> Subject: Re: Tomcat latency
>
>
> Yes, 1.6.0_24 is the latest. I believe the only changes from _22 were
> security fixes, though.
>
>
1.6.0_25 is the latest. And 1.7.0 is in final build stages and is stable.
david
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Re: Tomcat latency
Posted by David kerber <dc...@verizon.net>.
On 5/26/2011 10:17 AM, Christopher Schultz wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> To whom it may concern,
>
> On 5/23/2011 10:45 PM, tomcat@r322.com wrote:
>> I have a problem where a simple wget call to docs/config/valve.html can
>> sometimes take up to 15 seconds to process.
>
> :(
>
>> I have a script that does a wget call to valve.html every 5 seconds.
>> Most of the time it's fast. However, today in the past 6 hours I had 13
>> cases where it took over 3 seconds for wget to return valve.html. This
>> is happening across 7 servers pretty consistently and I can't figure out
>> why. Any suggestions to help me narrow down the problem?
>
> Can you run sar/iostat/vmstat/etc. simultaneously and graph the system
> values against your wget response times? You may find that something is
> spiking the CPU, I/O, NIC, etc. at those times.
>
> Are you on a virtual machine, perhaps? I've found that VMs (particularly
> OpenVZ and other Virtuozzo-derived flavors) are notorious for having
> bizarre I/O stalls on the virtual containers.
>
>> Server version: Apache Tomcat/6.0.20
>
> It certainly couldn't hurt to upgrade to the most recent version: Tomcat
> 6.0.32. Remember to carefully read the changelog.
>
>> JVM Version: 1.6.0_22-b04
>> JVM Vendor: Sun Microsystems Inc.
>
> It probably won't make a difference, but I believe that's a version or
> two behind as well.
Yes, 1.6.0_24 is the latest. I believe the only changes from _22 were
security fixes, though.
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Re: Tomcat latency
Posted by Christopher Schultz <ch...@christopherschultz.net>.
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
To whom it may concern,
On 5/23/2011 10:45 PM, tomcat@r322.com wrote:
> I have a problem where a simple wget call to docs/config/valve.html can
> sometimes take up to 15 seconds to process.
:(
> I have a script that does a wget call to valve.html every 5 seconds.
> Most of the time it's fast. However, today in the past 6 hours I had 13
> cases where it took over 3 seconds for wget to return valve.html. This
> is happening across 7 servers pretty consistently and I can't figure out
> why. Any suggestions to help me narrow down the problem?
Can you run sar/iostat/vmstat/etc. simultaneously and graph the system
values against your wget response times? You may find that something is
spiking the CPU, I/O, NIC, etc. at those times.
Are you on a virtual machine, perhaps? I've found that VMs (particularly
OpenVZ and other Virtuozzo-derived flavors) are notorious for having
bizarre I/O stalls on the virtual containers.
> Server version: Apache Tomcat/6.0.20
It certainly couldn't hurt to upgrade to the most recent version: Tomcat
6.0.32. Remember to carefully read the changelog.
> JVM Version: 1.6.0_22-b04
> JVM Vendor: Sun Microsystems Inc.
It probably won't make a difference, but I believe that's a version or
two behind as well.
- -chris
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