Performance Testing Tools

Today i want to share a command ss (Socket statistics) to investigate network and debug tcp connections. ss  is  used to dump socket statistics. It allows showing information similar to netstat.  It can display more TCP and state information than other tools. It is present in most of our Linux machines.
ss commands has lot of options. To get all options: ss -help
Few commands and outputs worth trying are as below: ss -t ->stands for tcp. Gives information about tcp connections that are available on the system #ss -t State       Recv-Q Send-Q                                Local Address:Port                                                 Peer Address:Port ESTAB       0      352                                   172.19.79.104:ssh                                                172.29.155.168:64045 ESTAB       0      0                                     172.19.79.104:54550                                               172.19.79.105:pcsync-https ESTAB       0      0               …

Initial basic checks before proceeding to DB tunings in MSSQL:
Check your SQL Server environment before tuning for performance
Sometimes when we have issues with slow response for our DB queries, we think of tuning the query assuming the SQL Server is tuned and it may be problem with queries. But it is observed that it is better to make a common practice to check the basic configuration settings of the SQL server before we start to analyze the queries deeper. Today i will try to touch base some of those settings which we always need to check for proper settings of the SQL server Environment.
Check 1: Database and Transaction log files on separate drives To obtain optimal SQL performance, it is recommended to separate the data and the log files onto separate physical drives. Placing both data AND log files on the same device can cause contention for that device, resulting in poor performance. Placing the files on separate drives allows the I/O activity to occur at the same time for both th…

While running our jmeter load tests on Unix box with a target of 2500 User Load we got the exception “Non HTTP response code: java.net.NoRouteToHostException,Non HTTP response message: Cannot assign requested address” in jmeter log
We have set open files limit to 50000 and ran the test, but still we were getting the errors.
$ ulimit -a core file size          (blocks, -c) 0 data seg size           (kbytes, -d) unlimited scheduling priority             (-e) 0 file size               (blocks, -f) unlimited pending signals                 (-i) 31182 max locked memory       (kbytes, -l) 64 max memory size         (kbytes, -m) unlimited open files                      (-n) 50000 pipe size            (512 bytes, -p) 8 POSIX message queues     (bytes, -q) 819200 real-time priority              (-r) 0 stack size              (kbytes, -s) 8192 cpu time               (seconds, -t) unlimited max user processes              (-u) 4096 virtual memory          (kbytes, -v) unlimited file locks                      (-…

In one of our project we have more than 4 Windows servers. We use perfmon to monitor the resource utilization. Each time we run load test we start the perfmon on all the servers.
So created the below batch file to do the job.

The batch file does the below: Create a directory with current date and timeStart perfmon on all 4 AR serversWait for 1 hrCopy the result file (.csv) from each server into the director created in step1.Stop perfmon on all 4 AR servers.
@echo off
for /f %%I in ('wmic os get localdatetime ^|find "20"') do set dt=%%I REM dt format is now YYYYMMDDhhmmss... REM set dt=%dt:~4,2%-%dt:~2,2%-%dt:~0,4%
set dt=%dt:~6,2%%dt:~4,2%%dt:~2,2%%dt:~8,2%%dt:~10,2% echo %dt%
mkdir D:\Perfmon\Perfmon_%dt%
logman start "Counter" -s server1 logman start "Counter" -s server2 logman start "Counter" -s server3 logman start "Counter" -s server4
timeout /t 3600
copy \\server1\c$\PerfLogs\Admin\Counter\*%dt%*.csv D:\Perfmon\Perfmon_%dt…

In Sun JDK there were few bugs previously with subject “JDK-6872335 : NewRatio ignored when UseConcMarkSweepGC set”.
http://bugs.java.com/view_bug.do?bug_id=6872335 http://bugs.java.com/view_bug.do?bug_id=6862534
Although these bugs are fixed, but IMO the bug still exists for default settings of NewRatio when UseConcMarkSweepGC is used.

We still have the bug where the default NewRatio=2 is not considered along with UseConcMarkSweepGC
Option #1 : Default GC (-XX:+UseParallelGC) : PSYoungGen      total 1835008K = 1.75GB (As it considered the default NewRatio=2) # /usr/bin/java -server -Xms6144m -Xmx6144m -XX:MaxMetaspaceSize=256m -XX:+PrintCommandLineFlags -XX:+PrintGCDetails -version -XX:InitialHeapSize=6442450944 -XX:MaxHeapSize=6442450944 -XX:MaxMetaspaceSize=268435456 -XX:+PrintCommandLineFlags -XX:+PrintGCDetails -XX:+UseCompressedClassPointers -XX:+UseCompressedOops -XX:+UseParallelGC java version "1.8.0_60" Java(TM) SE Runtime Environment (build 1.8.0_60-b27) Java HotSpot(TM) 64…