{ Make this readable }

Thursday, April 28, 2011

DSLs, OODBs, system internals and some Java stuff


DSLs:

  • Groovy is perhaps the best language that lends itself for this purpose. Here's a nice (longish) introduction - Groovy.DSLs (from: beginner, to: expert) 
  • A simpler pseudo DSL based on regex - Jbehave, primarily used for Behaviour-driven development in Java
A good article by (The) Martin Fowler on how to develop quality code - for beginners.

A few good articles I came across recently on operating systems, disks, networking:
OODBs - NoSql's grandpa and the forgotten cousin of SQL. Haven't even heard of OODBs? Here's a 4 year old article but still worth reading.

Java tidbits:

Wednesday, April 20, 2011

You know you are growing old(er) when you catch yourself listening to the news more often than music, while driving.

Thursday, April 07, 2011

The little gem that is BusyBox (for Windows)

As a Windows user (no shame) I have, for years searched for a simple GNU-like toolkit - grep, awk, tail and other such goodies enjoyed by Linux users. Yes, there's Cygwin but it's a beast - too big and a pain to install. Sometimes, I've even resorted to starting a Linux VMWare image just to run a simple awk script to munge some log files.

But today...today I found BusyBox and there's a compact 600KB BusyBox exe for Windows! What does it have? Well.. what does it not have?! It has all the essentials:

[, [[, ar, ash, awk, base64, basename, bash, bbconfig, bunzip2, bzcat,
bzip2, cal, cat, catv, cksum, cmp, comm, cp, cpio, cut, date, dc, dd,
diff, dirname, dos2unix, echo, ed, egrep, env, expand, expr, false,
fgrep, find, fold, getopt, grep, gunzip, gzip, hd, head, hexdump, kill,
killall, length, ls, lzcat, lzma, lzop, lzopcat, md5sum, mkdir, mv, od,
pgrep, pidof, printenv, printf, ps, pwd, rm, rmdir, rpm2cpio, sed, seq,
sh, sha1sum, sha256sum, sha512sum, sleep, sort, split, strings, sum,
tac, tail, tar, tee, test, touch, tr, true, uncompress, unexpand, uniq,
unix2dos, unlzma, unlzop, unxz, unzip, usleep, uudecode, uuencode, vi,
wc, wget, which, whoami, xargs, xz, xzcat, yes, zcat
This is where I'd use it the most - to compress and summarize JVM thread dumps for quick analysis. It's based on JPMP, but here's my version of it. First, download BusyBox for Windows and then use the simple script below to munge your JVM thread dump.

This is the first part of the script:
This is the awk pattern that is used by the script above.
All you have to do now is run it against your thread dump file:
jpmp.bat ..\jstack.out > ..\jstack.out.log

And it converts a huge file like this...
2011-04-07 20:44:06
Full thread dump Java HotSpot(TM) 64-Bit Server VM (16.2-b04 mixed mode):

"TimerQueue" daemon prio=6 tid=0x000000004ec33000 nid=0x1268 in Object.wait() [0x000000004a3cf000]
   java.lang.Thread.State: WAITING (on object monitor)
 at java.lang.Object.wait(Native Method)
 - waiting on <0x0000000034004608> (a javax.swing.TimerQueue)
 at javax.swing.TimerQueue.run(TimerQueue.java:232)
 - locked <0x0000000034004608> (a javax.swing.TimerQueue)
 at java.lang.Thread.run(Thread.java:619)

"D3D Screen Updater" daemon prio=8 tid=0x000000004af1e000 nid=0x186c in Object.wait() [0x000000004f40f000]
   java.lang.Thread.State: TIMED_WAITING (on object monitor)
 at java.lang.Object.wait(Native Method)
 - waiting on <0x0000000034e16ba8> (a java.lang.Object)
...
...
...
...
"Reference Handler" daemon prio=10 tid=0x0000000000823800 nid=0x18e4 in Object.wait() [0x000000004940f000]
   java.lang.Thread.State: WAITING (on object monitor)
 at java.lang.Object.wait(Native Method)
 - waiting on <0x0000000034dda018> (a java.lang.ref.Reference$Lock)
 at java.lang.Object.wait(Object.java:485)
 at java.lang.ref.Reference$ReferenceHandler.run(Reference.java:116)
 - locked <0x0000000034dda018> (a java.lang.ref.Reference$Lock)

"VM Thread" prio=10 tid=0x0000000000820000 nid=0x14c4 runnable 

"GC task thread#0 (ParallelGC)" prio=6 tid=0x0000000000777800 nid=0x173c runnable 

"GC task thread#1 (ParallelGC)" prio=6 tid=0x0000000000779800 nid=0x4b8 runnable 

"GC task thread#2 (ParallelGC)" prio=6 tid=0x000000000077b000 nid=0x15d0 runnable 

"GC task thread#3 (ParallelGC)" prio=6 tid=0x000000000077c800 nid=0x199c runnable 

"VM Periodic Task Thread" prio=10 tid=0x0000000049580800 nid=0x1984 waiting on condition 

JNI global references: 1355

Into a tidy summary like this. Very useful if you have thread dumps from 20 servers taken every 30 seconds.
All this without leaving the comfort of your Windows system!
2 j.lang.Object.wait,j.io.PipedInputStream.read,j.io.PipedInputStream.read,sun.nio.cs.StreamDecoder.readBytes,sun.nio.cs.StreamDecoder.implRead,sun.nio.cs.StreamDecoder.read,j.io.InputStreamReader.read,j.io.BufferedReader.fill,j.io.BufferedReader.readLine,j.io.BufferedReader.readLine,sun.tools.jconsole.OutputViewer$PipeListener.run
1 sun.awt.windows.WToolkit.eventLoop,sun.awt.windows.WToolkit.run,j.lang.Thread.run
1 j.lang.Object.wait,sun.java2d.d3d.D3DScreenUpdateManager.run,j.lang.Thread.run
1 j.lang.Object.wait,jx.swing.TimerQueue.run,j.lang.Thread.run
1 j.lang.Object.wait,j.lang.ref.ReferenceQueue.remove,j.lang.ref.ReferenceQueue.remove,sun.java2d.Disposer.run,j.lang.Thread.run
1 j.lang.Object.wait,j.lang.ref.ReferenceQueue.remove,j.lang.ref.ReferenceQueue.remove,j.lang.ref.Finalizer$FinalizerThread.run
1 j.lang.Object.wait,j.lang.Object.wait,sun.awt.AWTAutoShutdown.run,j.lang.Thread.run
1 j.lang.Object.wait,j.lang.Object.wait,j.lang.ref.Reference$ReferenceHandler.run
1 j.lang.Object.wait,j.lang.Object.wait,j.awt.EventQueue.getNextEvent,j.awt.EventDispatchThread.pumpOneEventForFilters,j.awt.EventDispatchThread.pumpEventsForFilter,j.awt.EventDispatchThread.pumpEventsForHierarchy,j.awt.EventDispatchThread.pumpEvents,j.awt.EventDispatchThread.pumpEvents,j.awt.EventDispatchThread.run

Until next time!