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From <Feltin_Thie...@emc.com>
Subject RE: Monitoring low level IO
Date Fri, 04 Jun 2010 10:50:45 GMT
If you are running with a Sun JVM 1.6, one possible way is to monitor the low level JVM java
IO calls using BTrace (See http://kenai.com/projects/btrace/pages/Home). This is kind of lightweight
custom java profiler.
 
It's quite easy to setup but will require that you know what IO calls are involved to write
a few java lines to track what you need to.

For example to track the reads calls start/end including the duration:

@OnMethod(clazz = "java.io.RandomAccessFile", method = "read")
public static void onRandomReadStart() {
  print(timestamp("y/M/d HH:mm:ss.SSS"));  
  print(strcat(", ", name(currentThread())));
  print(strcat(", ", "IO read start");
}

@OnMethod(clazz = "java.io.RandomAccessFile", method = "read", location=@Location(value=Kind.RETURN))
public static void onRandomReadEnd(@Duration long d) {
  print(timestamp("y/M/d HH:mm:ss.SSS"));  
  print(strcat(", ", name(currentThread())));
  print(strcat(", ", str(d));
  print(strcat(", ", "IO read end");
}





-----Original Message-----
From: Jason Rutherglen [mailto:jason.rutherglen@gmail.com] 
Sent: jeudi 3 juin 2010 20:13
To: java-user@lucene.apache.org
Subject: Monitoring low level IO

This is more of a unix related question than Lucene specific
however because Lucene is being used, I'm asking here as perhaps
other people have run into a similar issue.

On an Amazon EC2 merge, read, and write operations are possibly
blocking due to underlying IO. Is there a tool that you have
used to monitor this type of thing?

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