Linux: Use Tomcat native libs (minor performance increase)

as root:

• Bash

Restart tomcat, then logs should show:

• logs

Tomcat connector settings

Following values can be set in /opt/tomcat/conf/server.xml, <Connector> part:

• maxThreads: default 200,

• connectionTimeout: Must be as high as a complete deploy on all nodes lasts to prevent connection timeouts during this longest request

Yambas.conf

• mongodbConnections: 100 is default; this value is multiplied by the number of app servers; that is, if you have 3 appservers, we have 300 open connections to database. Measurements showed 100 to be a good value.

• maxResults: maximum number of results to return per query (for more, LIMIT/OFFSET must be used). Default: 1000. Setting this value too high may lead to blocking operations in database if indexes are missing

JVM

Values are set in /etc/apiomat/tomcat7:

• -XX:+UseSerialGC - improves speed in contrast to XX:+UseConcMarkSweepGC

• -Xmx12g - sets the max available memory for java. Should be about 80% of the machines RAM (12GB in this example)

• -Xms12g - sets the initial memory for java. Should be as high as Xmx for most installations (12GB in this example)

Logs

Set Apiomat logs to WARN in log4j.xml!

Indexes

By default, all queries lasting longer than 300 ms are logged to /var/log/mongodb/mongod.log.

To get more information and specifiy the time which queries should be logged, use the profiler:

1. Go to the applications database

2. The following command will catch each command which lasts longer than 1000ms:

   • log

   db.setProfilingLevel(1, 1000);

   http://docs.mongodb.org/manual/reference/method/db.setProfilingLevel/#db.setProfilingLevel

   Or print all commands, not only the slow ones:

   • mongo

   db.setProfilingLevel(2,0);

3. Look into the profiling collections to see the queries:

   • mongo

   db.system.profile.find()

4. To see only the last results sorted by date:

   • mongo

   db.system.profile.find().limit(10).sort( { ts : -1 } ).pretty()

5. Add indexes for every result which has a high value at " nscanned" or has type "collscan"

More info:

• Profiler: http://docs.mongodb.org/manual/tutorial/manage-the-database-profiler/

• Interpret profiler output: http://docs.mongodb.org/manual/reference/database-profiler/