Performance Analysis and Troubleshooting
This is a page to assist with performance analysis and troubleshooting.
Contents
Monitoring Deadlocks in PostgreSQL
You can monitor any database locks using the Entity SQL Processor in Webtools -> Entity SQL Processor with the following query,
select pg_class.relname, pg_locks.mode, pg_locks.relation, pg_locks.transaction, pg_locks.pid
from pg_class, pg_locks
where pg_class.relfilenode = pg_locks.relation
order by pid
This will show what kinds of locks are active on what entities. If there is an exclusive lock on a table followed by a bunch of pids that are waiting for it, then you have a deadlock.
Suspending Runaway Threads
Suppose you start a process that you realize will take forever and need to stop it. However, it can't be stopped because it was activated by an HTTP request and killing the browser session doesn't work. First, check the log to see if you can identify the thread that is running this process. For instance, suppose you have the following line in your log that corresponds to what your process is doing,
2008-01-23 18:55:47,585 (TP-Processor10) [ Something.java:1015:WARN ] Something that identifies your process
This thread is TP-Processor10. You can use the Java Thread API to suspend it by hand. The easiest way to do this is to use a bsh script or the bsh terminal. First, you will want to know the number of threads in the system. Load up Webtools -> Jobs -> Thread List and count the rough number of threads displayed. Suppose you have about 50 threads.
Once you know the rough size, run the following script, either via the bsh terminal or by hooking it up to a controller.xml request,
threads = new Thread[50];
size = Thread.enumerate(threads);
for (i = 0; i < size; i++) {
print(i + ": " + threads[i]);
}
This will print out the index and name of each thread. Find the index of TP-Processor 10. Suppose it is index 37. You can then suspend the thread by doing this,
t = threads[37]; t.suspend();
AspectJ Profiling
How to use AspectJ profiling method, and how is it done?
Compile and run AspectJ profiling
You compile it
$ ant -f hot-deploy/opentaps-common/build.xml profiling
and then you run the test. Be careful by default, ofbiz build the whole project before running the test. You have to delete this dependencies to keep aspectJ changes.
$ ant run-tests
Then when you look at the logs, you have:
- A confirmation the profiling library is loaded.
Example:
* Start JETM monitoring * JETM 1.2.2 started.
- A table with all the profiling details.
Example:
Understand AspectJ code
- Some theory:
First you have to create a file with your aspect. We are not talking anymore about class, but aspect. Actually, it use a specific compiler. (Compiler errors message are not really understandable in my mind...)
AOP is a way to add code to several points of the project, based on method selections or pointcut.
Creation of a poincut:
pointcut testRunContainerStart() : execution(public boolean org.ofbiz.testtools.TestRunContainer.start());
You can use wildcard: *, +, ..
* replace a name or part of the name
public * fr.umlv.*.test.*.start*(int, String, *)
+ used to not tell the name of the parameter of the method or the name of the package
public void fr..Test.SetParams(..) all the public method of SetParam whatever are their parameters, returning void and available in the classes Test which are wherever in the package fr
.. used to define whatever sub-type of a class or interface.
void fr.umlv.test.IMouseListener+.set*(..) all the methods which begins with set in the classes implementing the interface IMouseListener.
- Some Practical comments:
In my case I almost always give the full method name with the argument. Because ofbiz and opentaps project are big projects, side effects could happen in case of not specifing the full method name I want to work on.
- Let's go back to theory:
You can define the poincut on various events: call, execution, get, set, handler, initialization, preinitialization, staticinitialization, adviceexecution
call call of the method
execution execution of the method.
- What is the difference between call and execution?
Mainly it is about heritance. In the case of call we are working with the reference which is used in the program (it can be the interface). In the case of execution we are working on the object which is instanciated.
- During the creation of a pointcut, you can use logic and associatevarious call, execution with && or ||
The interesant method is args which let you access to the parameter of the method.
- When you pointcut is defined, you can realize a treatment.
before to realize the treatment before to reach the pointcut.
after to realize the treatment after to reach the pointcut.
- If the program is multithread (case of opentaps) and you have to do two
treatment before and after the pointcut, you can use around and proceed. proceed will execute the code corresponding to the poincut in a around instruction.
- This is a really quick overview, to understand the code added to
opentaps and there is some more to know, some trap (infinite loops) etc...
