Difference between revisions of "Java"

Revision as of 08:29, 13 January 2015

Profiling

-Xrunhprof:cpu=samples,file=/tmp/app-profile.txt -jar foo.jar

OpenJDK Heapdump

sudo yum install java-1.6.0-openjdk-devel
sudo jmap -F -J-d64 -dump:live,format=b,file=/root/heap.bin 2232
sudo jstack -F 2232 > /root/stacks.txt

sudo -u tomcat jmap -J-d64 -dump:format=b,file=/tmp/heap.bin 1384

• http://linux.die.net/man/1/jmap-java-1.6.0-openjdk
• http://www.eclipse.org/mat/
• http://vault.centos.org/6.4/updates/x86_64/Packages/

Remote Debug Tomcat6

In /usr/sbin/tomcat6:

-Xdebug -Xrunjdwp:transport=dt_socket,address=62277,server=y,suspend=n

GC

• http://mechanical-sympathy.blogspot.co.uk/2013/07/java-garbage-collection-distilled.html
• http://www.oracle.com/technetwork/java/javase/gc-tuning-6-140523.html

sudo jmap -heap <pid>

java \
  -Xms300m \
  -Xmx600m \
  -verbose:gc \
  -XX:MaxGCPauseMillis=20 \
  -XX:+UseConcMarkSweepGC \
  -XX:+CMSIncrementalMode \
  -XX:+CMSIncrementalPacing \

java \
  -verbose:gc \
  -XX:+PrintGCDetails \
  -XX:MaxGCPauseMillis=20 \
  -XX:MaxGCMinorPauseMillis=10 \
  -XX:GCTimeRatio=200 \
  -XX:+UseSerialGC \
  -Xms140m -Xmx140m \

• http://stas-blogspot.blogspot.co.uk/2011/07/most-complete-list-of-xx-options-for.html
• https://blog.codecentric.de/en/2013/01/useful-jvm-flags-part-6-throughput-collector/