svanoort

# custom IntelliJ IDEA VM options
-server
-Xss16m
-Xms256m
-Xmx1500m
-XX:ReservedCodeCacheSize=240m
-XX:+AlwaysPreTouch
-XX:+TieredCompilation
-XX:+UseCompressedOops
-XX:+UseCompressedClassesPointers

svanoort

# Base settings and GC logging
-server -XX:+AlwaysPreTouch  # First should be default, but we make it explicit, second pre-zeroes memory mapped pages on JVM startup -- improves runtime performance
# -Xloggc:gc-%t.log  # CUSTOMIZE LOCATION HERE - $path/gc-%t.log -- the %t in the gc log file path is so we get a new file with each JVM restart
-XX:NumberOfGCLogFiles=5 -XX:+UseGCLogFileRotation -XX:GCLogFileSize=20m # Limits the number of files, logs to folder 
-XX:+PrintGC -XX:+PrintGCDateStamps -XX:+PrintGCDetails -XX:+PrintHeapAtGC -XX:+PrintGCCause
-XX:+PrintTenuringDistribution -XX:+PrintReferenceGC -XX:+PrintAdaptiveSizePolicy # gather info on object age & reference GC time for further tuning if needed.

# G1 specific settings -- probably should be default for multi-core systems with >2 GB of heap (below that, default is probably fine)
-XX:+UseG1GC
-XX:+UseStringDeduplication

svanoort

#!/bin/python
import sys
import re

# You'll need to extract JUST the table of pstools output (no headers!) from your pstools thread dumps for windows

print(sys.argv)
if not sys.argv[1] or not sys.argv[2]:
    print("Need to supply the path to the pstools before and after filenames")
    exit()

svanoort

// Test for handling of errors in nested blocks, and UI rendering of same
stage 'sample'
  node {
      dir('sample') {
          dir('more') {
              sh 'failme'
          }
      }
  }

svanoort

#!/bin/bash
# Curl the bandwidth test site for 10 MB file and get speed in bytes/second, reboot cable modem if <5 MBit
# Useful as bash alias that retests and triggers every hour: 
# alias continuously_speedtest='while [ true ]; do echo "Sleeping 1 hour and then speedtesting network"; sleep 3600; bash ~/speedtest-restart.sh; done'

set -o pipefail
echo 'Speedtesting modem now'
DOWN_SPEED=$(curl http://speedtest.wdc01.softlayer.com/downloads/test10.zip  -t 100 -o /dev/null -s -w "%{speed_download}" | sed -E "s/\.[0-9]+//g")
if [ "$?" -ne 0 ]; then
    echo "Speed test failed!"

svanoort

One source: http://developers.redhat.com/blog/2014/07/22/dude-wheres-my-paas-memory-tuning-javas-footprint-in-openshift-part-2/

# Set the XMX to cap your max heap, set the xms to a reasonable minimum
-Xmx384m -Xms100m

# No more than 40% of heap free, lowest GC overhead and keeps heap small - still under 0.5% GC time
seropt: 
-XX:+UseSerialGC -XX:MinHeapFreeRatio=20 -XX:MaxHeapFreeRatio=40

# parallel version, allows up to 4% time spent on GC, generally uses heap more efficiently, but at cost of 2x the CPU USE

svanoort

package hudson.cli;

import org.junit.Test;

import java.util.*;

// Micro benchmark different array ops in Java
// Originally started from http://stackoverflow.com/questions/322715/when-to-use-linkedlist-over-arraylist/7507740#7507740
// Now completely rewritten to correctly warm up the JIT compilation and take an average over many runs
// Tweaked/corrected version from http://stackoverflow.com/questions/322715/when-to-use-linkedlist-over-arraylist/7507740#7507740