squirrel-sql-users

[Squirrel-sql-users] High thread count -- is this normal?

[David H. <dh...@23...>]

I only recently noticed that squirrel-sql is creating a really large number
of threads -- if I just fire up the application and don't open a
connection, I get 49 java threads.  Is this expected?

I'm running the 3.3.0 release with a 64-bit OpenJDK 1.6.0

I noticed because I've started running into a system limit on number of
user processes and wanted to determine if this is normal before I ask for
the limit to be raised.  I use squirrel-sql intermittently but it is only
in the past few days that I've started running into this limit, which
suggests that something has changed, but I can't think of what.

- Dave

Re: [Squirrel-sql-users] High thread count -- is this normal?

[Stefan W. <ste...@ao...>]

Hi Dave,

I can't answer the question, if 49 java threads are normal. This depends 
on the state of SQuirreL. E.g. how many Sessions are open and so on.

If I start SQuirrel and open a connection, then I have 26 threads running.
There are threads for:
* Our thread pool
* Garbage Collection
* Swing
and so on.

 From a previous bug, we know, that we have some issues with OpenJDK. 
This is, because OpenJDK is a little bit more restrictive to the "Event 
Dispatch Thread Rule" of Swing than Oracles JRE. In our latest snapshot 
release, we have fixed some issues depending on this problem and 
introduced a new plugin called "SwingViolations" to detect this 
problems. So maybe, you can try our current snapshot release to see, if 
there is a difference.

With a thread dump from your running SQuirreL process, we can estimate, 
if your number of threads is normal. You can do a thread dump by 
"jvisualvm" which is part of your JDK.

Stefan



Am 2012-06-01 18:58, schrieb David Hinds:
> I only recently noticed that squirrel-sql is creating a really large 
> number of threads -- if I just fire up the application and don't open 
> a connection, I get 49 java threads.  Is this expected?
>
> I'm running the 3.3.0 release with a 64-bit OpenJDK 1.6.0
>
> I noticed because I've started running into a system limit on number 
> of user processes and wanted to determine if this is normal before I 
> ask for the limit to be raised.  I use squirrel-sql intermittently but 
> it is only in the past few days that I've started running into this 
> limit, which suggests that something has changed, but I can't think of 
> what.
>
> - Dave
>
>
>
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Re: [Squirrel-sql-users] High thread count -- is this normal?

[David H. <dh...@23...>]

Stefan Willinger <stefan.home <at> aon.at> writes:
>
>     Hi Dave,
>     I can't answer the question, if 49 java threads are normal. This
>     depends on the state of SQuirreL. E.g. how many Sessions are open
>     and so on.
>     If I start SQuirrel and open a connection, then I have 26 threads
>     running.
...
>     With a thread dump from your running SQuirreL process, we can
>     estimate, if your number of threads is normal. You can do a thread
>     dump by "jvisualvm" which is part of your JDK.
>     Stefan

Ahh... I got it.  The 49 threads were immediately after starting up SQuirreL, 
with no open sessions.  I ran the thread dump, and I see that I have 32 GC 
threads, which seems a bit excessive.  This system was recently upgraded from
a dual-4-core system to dual-8-core with hyperthreading, so it appears as a 32
processor system.  So, I may need to use a -XX:ParallelGCThreads=n option.

-- Dave