Skip to main content

Contextual Thread dumps

Due to some business policy changes we recently started seeing some changes in usage pattern of our application leading to unexplained app node spikes. These spikes were temporary and by the time we go and try to take jstacks it might have disappeared. So we configured a quartz job to take jstack every 5 min(wrote a quartz instead of cron because cron needs to be manually configured on each node and we have tons of nodes to ops was always missing or misconfiguring it) and dump it in to a folder and we keep last 500 copies. That way I can go and correlate what was going on in the tomcat during the time of the spike (I had to get lucky for spike to happen when quartz job was running but I was lucky as most spikes spanned 3-5 mins). Now from those thread dumps I can figure out what was going on like how many thread are doing "searches" v/s how many thread are coming from Webdav or how many threads are doing add file. But one question that keep on coming was who are the customers who are doing them. For e.g. if we saw 50 threads doing webdav propfinds, it would be good to know if most of these requests are coming from same customer or diff customer. So I went and added customer domain name to each thread in a servlet filter for each incoming request. This helped me find issues at a much faster rate as I no longer need to go and correlate it in the logs as to what thread was doing at that time. I found lots of patterns by just adding contextual information to threads. Below is how the information is in the thread name.

Thread[http-6280-Processor169|D-avlapp05,5,main]
RUNNABLE

      
   at java.lang.Thread.dumpThreads(Native Method)
   at java.lang.Thread.getAllStackTraces(Thread.java:1487)
   at com.sslinc.infrastructure.perf.ThreadDumpBean.(ThreadDumpBean.java:17)
   at org.apache.jsp.static_.admin.threadDump_jsp._jspService(threadDump_jsp.java:58)
   at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
   at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
   at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689)
   at java.lang.Thread.run(Thread.java:619)
      

Thread[multi-file-upload-commit-a5611a5a-3e5a-44ee-a005-8042ee732d9d-13900185618|D-krisgsc1,5,main]
WAITING

      
   at sun.misc.Unsafe.park(Native Method)
   at java.util.concurrent.locks.LockSupport.park(LockSupport.java:158)
   at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:1925)
   at java.util.concurrent.LinkedBlockingQueue.take(LinkedBlockingQueue.java:358)
   at com.sslinc.ui.web.servlet.UploadProcessThread.run(UploadProcessThread.java:120)

Comments

Post a Comment

Popular posts from this blog

RabbitMQ java clients for beginners

Here is a sample of a consumer and producer example for RabbitMQ. The steps are Download Erlang Download Rabbit MQ Server Download Rabbit MQ Java client jars Compile and run the below two class and you are done. This sample create a Durable Exchange, Queue and a Message. You will have to start the consumer first before you start the for the first time. For more information on AMQP, Exchanges, Queues, read this excellent tutorial http://blogs.digitar.com/jjww/2009/01/rabbits-and-warrens/ +++++++++++++++++RabbitMQProducer.java+++++++++++++++++++++++++++ import com.rabbitmq.client.Connection; import com.rabbitmq.client.Channel; import com.rabbitmq.client.*; public class RabbitMQProducer { public static void main(String []args) throws Exception { ConnectionFactory factory = new ConnectionFactory(); factory.setUsername("guest"); factory.setPassword("guest"); factory.setVirtualHost("/"); factory.setHost("127.0.0.1"); factory.se...
23 comments
Read more

Spring 3.2 quartz 2.1 Jobs added with no trigger must be durable.

I am trying to enable HA on nodes and in that process I found that in a two test node setup a job that has a frequency of 10 sec was running into deadlock. So I tried upgrading from Quartz 1.8 to 2.1 by following the migration guide but I ran into an exception that says "Jobs added with no trigger must be durable.". After looking into spring and Quartz code I figured out that now Quartz is more strict and earlier the scheduler.addJob had a replace parameter which if passed to true would skip the durable check, in latest quartz this is fixed but spring hasnt caught up to this. So what do you do, well I jsut inherited the factory and set durability to true and use that public class DurableJobDetailFactoryBean extends JobDetailFactoryBean {     public DurableJobDetailFactoryBean() {         setDurability(true);     } } and used this instead of JobDetailFactoryBean in the spring bean definition     <bean i...
7 comments
Read more

Killing a particular Tomcat thread

Update: This JSP does not work on a thread that is inside some native code.  On many occasions I had a thread stuck in JNI code and it wont work. Also in some cases thread.stop can cause jvm to hang. According to javadocs " This method is inherently unsafe. Stopping a thread with Thread.stop causes it to unlock all of the monitors that it has locked". I have used it only in some rare occasions where I wanted to avoid a system shutdown and in some cases we ended up doing system shutdown as jvm was hung so I had a 70-80% success with it.   -------------------------------------------------------------------------------------------------------------------------- We had an interesting requirement. A tomcat thread that was spawned from an ExecutorService ThreadPool had gone Rogue and was causing lots of disk churning issues. We cant bring down the production server as that would involve downtime. Killing this thread was harmless but how to kill i...
6 comments
Read more