Hi all
When we introduce load balancing and a 2nd tomcat worker, the time
to service client requests is not balanced. Some clients are serviced as
above,
but others may take 10, 20, 30 seconds or more. Eventually, clients timeout
and sessions are lost.
We ran our test over night with just 20 clients. All requests were serviced
evenly and we experienced no timeouts. However, the attached jkstatus
page shows some interesting results. The 'Busy' and 'Max' values for
the two workers are vastly different. For worker1, these values just
keep incrementing. Also, worker2 has serviced way more requests.
The 'Busy' and 'Max Busy' numbers in the other table keep growing
as well. Is this behaviour normal? or does this point to a problem
somewhere in the configuration?
As we add more clients, the time it takes to service requests gets more and
more imbalanced. Some requests get serviced in < 1 second, others can
take 20 or 30 seconds. The more clients we add, the longer it takes for
some requests to get serviced.
We are using apache 2.26, mod_jk 1.2.26 and tomcat 6.0.14 , JRE 1.5_06-b05
Apache and worker1 are on the same box. worker2 is in a different box
We are relly new on this(balancer), as you can see below we were using
tomcat 5.5.20 , apache 2.2.0 and mod_jk 1.2.25 so we updated them all ,
but still same problems
Thanks a lot for your help
Rainer Jung wrote:
Julio Cesar Leiva schrieb:
Hi all
We have this setup
1 web server apache 2.2.0
I hope it's not 2.2.0 but something more recent (e.g. 2.2.4 or 2.2.6)
2 tomcat servers tomcat 5.5.20
mod_jk 1.2.25
This is our workers.properties
Remove the next line, it's useless.
workers.java_home=/usr/lib64/jvm/java
worker.list=cbnbalancer,jkstatus
Maybe add connect_timeout and prepost_timeout to the next two, and if
it makes sense for the app also reply_timeout. See
http://tomcat.apache.org/connectors-doc/generic_howto/timeouts.html
# Set properties for worker1 (ajp13)
worker.worker1.type=ajp13
worker.worker1.host=172.20.23.12
worker.worker1.port=8009
worker.worker1.lbfactor=1
#worker.worker1.connection_pool_timeout=600
#worker.worker1.socket_keepalive=1
#worker.worker1.socket_timeout=60
worker.worker1.socket_timeout=0
# Define prefered failover node for worker1
worker.worker1.redirect=worker2
# Set properties for worker2 (ajp13)
worker.worker2.type=ajp13
worker.worker2.host=172.20.21.211
worker.worker2.port=8009
worker.worker2.lbfactor=1
#worker.worker2.connection_pool_timeout=600
#worker.worker2.socket_keepalive=1
#worker.worker2.socket_timeout=60
worker.worker2.socket_timeout=0
# Define prefered failover node for worker2
worker.worker2.redirect=worker1
method T (Traffic) does only make sense, if you are bandwidth limited
in the network and thus want to balance w.r.t bytes transferred.
# Set properties for balancer which use worker1 and worker2
worker.cbnbalancer.type=lb
worker.cbnbalancer.method=T
worker.cbnbalancer.balance_workers=worker2,worker1
# Enable sticky-sessions (aka session affinity)
worker.cbnbalancer.sticky_session=1
# Define a 'jkstatus' worker using status
worker.jkstatus.type=status
# Add the jkstatus mount point
Maybe a little simpler, if you omit the trailing '*', thus mapping the
exact URL /jkmanager/.
JkMount /jkmanager/* jkstatus
# Enable the JK manager access from localhost only
<!-- Location /jkmanager/>
You don't need the next line, because you already defined this mount.
JkMount jkstatus
Order deny,allow
Deny from all
# Allow from 127.0.0.1
Allow from all
</Location -->
This is part of one server.xml
connectionTimeout=600000 would be a good fit to the 600 in your jk
configuration.
2000 Threads is a lot, are you sure, that your OS can create that many
Threads for a JVM (Memory issues possible)? If you only allow 700
parallel requests in Apache, you don't need more than 700 (+1?)
threads in the AJP connector.
<Engine name="Catalina" defaultHost="localhost" jvmRoute="worker1" >
<Connector port="8009" minProcessors="5" maxThreads="2000"
minSpareThreads="100" maxSpareThreads="150" maxProcessors="0"
protocol="AJP/1.3" connectionTimeout="0"/>
This is the second tomcat
<Engine name="Catalina" defaultHost="localhost" jvmRoute="worker2" >
<Connector port="8009" minProcessors="5" maxThreads="2000"
minSpareThreads="100" maxSpareThreads="150" maxProcessors="0"
protocol="AJP/1.3" connectionTimeout="0"/>
This is part of the apache conf
Which mpm, prefork?
# number of server processes to start
#
http://httpd.apache.org/docs/2.2/mod/mpm_common.html#startservers
StartServers 5
# minimum number of server processes which are kept spare
#
http://httpd.apache.org/docs/2.2/mod/prefork.html#minspareservers
MinSpareServers 5
# maximum number of server processes which are kept spare
#
http://httpd.apache.org/docs/2.2/mod/prefork.html#maxspareservers
MaxSpareServers 10
# highest possible MaxClients setting for the lifetime of the
Apache process.
#
http://httpd.apache.org/docs/2.2/mod/mpm_common.html#serverlimit
ServerLimit 700
# maximum number of server processes allowed to start
# http://httpd.apache.org/docs/2.2/mod/mpm_common.html#maxclients
MaxClients 700
# maximum number of requests a server process serves
#
http://httpd.apache.org/docs/2.2/mod/mpm_common.html#maxrequestsperchild
MaxRequestsPerChild 10000
We are trying to test this with 600 clients , when we reach 200 ,
everything gets stuck....
any ideas?
Thanks in advance four your help
JulioC.
How do clients relate to parallel requests?
What's the throughput before it gets stuck?
What does a Java Thread Dump of Tomcat tell you?
What is the status in the jk status worker?
Which kind of errors in the jk log do you get?
Regards,
Rainer
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JK Status Manager for 172.20.23.12:80
Server Version: Apache/2.2.6 (Linux/SUSE) mod_ssl/2.2.6 OpenSSL/0.9.8a
PHP/5.1.2 mod_jk/1.2.26
JK Version: mod_jk/1.2.26
Type lb
Sticky Sessions True
Force Sticky False
Sessions Retries 2
LB Method SEssions
Locking Optimistic
Recover 60
Wait Time 0
Max Replay 0
Timeouts 0
Good 2
Degraded 0
Bad/Stopped 0
Busy 1841
Max Busy 1854
Next Maintenance 22/84
Balance Members
Name worker1
Type ajp13
Host 172.20.21.211:8009
ADDR 172.20.21.211:8009
Act ACT
State OK
D 0
F 1
M 1
V 4
Acc 11833228
Err 0
CE 0
RE 0
Wr 6.0G
Rd 3.4G
Busy 32
Max 34
Route worker2
RR worker1
Cd Rs 0/0
Name worker2
Type ajp13
Host 172.20.23.12:8009
ADDR 172.20.23.12:8009
Act ACT
State OK
D 0
F 1
M 1
V 4
Acc 8911469
Err 0
CE 0
RE 0
Wr 4.5G
Rd 2.6G
Busy 1730
Max 1748
Route worker1
RR worker2
Cd Rs 0/0
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