is getAllStackTraces() something we are allowed to call from the server given the recent SecurityManager changes?

[Mike Matrigali]

Francois Orsini (JIRA) wrote:

[ http://issues.apache.org/jira/browse/DERBY-666?page=comments#action_12356460 ]

Francois Orsini commented on DERBY-666:
---------------------------------------

The new J2SE 5.0 has some new API to dump individual or all threads' 
stracktrace running in a JVM - There is a new notion of StackTraceElement 
object which represent a stack frame and can be output'ed as a String....

So you can get all frames of a particular thread's stack  dump as well as for 
all threads in the JVM.

http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Thread.html#getStackTrace()
http://java.sun.com/j2se/1.5.0/docs/api/java/lang/Thread.html#getAllStackTraces()

http://java.sun.com/j2se/1.5.0/docs/api/java/lang/StackTraceElement.html

Thread(s) stack dumps can also be performed on the command line using 'jstack' 
(1.5) utility to dump all the JVM's thread stack traces given a JVM pid.
http://java.sun.com/j2se/1.5.0/docs/tooldocs/share/jstack.html

fyi.

Enhance derby.locks.deadlockTrace to print stack traces for all threads 
involved in a deadlock
----------------------------------------------------------------------------------------------

        Key: DERBY-666
        URL: http://issues.apache.org/jira/browse/DERBY-666
    Project: Derby
       Type: Improvement
 Components: Store
   Versions: 10.1.1.0
   Reporter: Bryan Pendleton
   Priority: Minor

I was reading http://www.linux-mag.com/content/view/2134/ (good article, btw!), 
and it says:

 The next two properties are needed to diagnose concurrency (locking and 
deadlock) problems.

    *derby.locks.monitor=true logs all deadlocks that occur in the system.
    *derby.locks.deadlockTrace=true log a stack trace of all threads involved 
in lock-related rollbacks.

It seems, that, in my environment, the deadlockTrace property does not log a 
stack trace of *all* threads involved in the deadlock.
Instead, it only logs a stack trace of the *victim* thread involved in the 
deadlock.
I think it would be very useful if the derby.locks.deadlockTrace setting could 
in fact log a stack trace of all involved threads.
In a posting to derby-dev, Mike Matrigali noted that an earlier implementation 
of a similar feature had to be removed because it was too expensive in both 
time and space, but he suggested that there might be several possible ways to 
implement this in an acceptably efficient manner:

A long time ago there use to be room in each lock to point at a
stack trace for each lock, but that was removed to optimize the size
of the lock data structure which can have many objects outstanding.
And creating and storing the stack for every lock was incredibly slow
and just was not very useful for any very active application.  I think
I was the only one who ever used it.

The plan was sometime to add a per user data structure which could be
filled in when it was about to wait on a lock, which would give most of what is 
interesting in a deadlock.

The current deadlockTrace is meant to dump the lock table out to derby.log when 
a deadlock is encountered.

I agree getting a dump of all stack traces would be very useful, and
with the later jvm debug interfaces may now be possible - in earlier
JVM's there weren't any java interfaces to do so.  Does anyone have
the code to donate to dump all thread stacks to a buffer?

Mike also suggested a manual technique as a workaround; it would be useful to 
put this into the documentation somewhere, perhaps on the page which documents 
derby.locks.deadlockTrace? Here's Mike's suggestion:

What I do if I can reproduce easily is set try to catch the wait by
hand and then depending on the environment either send the magic
signal or hit ctrl-break in the server window which will send the JVM
specific thread dumps to derby.log.

The magic signal, btw, is 'kill -QUIT', at least with Sun JVMs in my experience.