CREATE TABLE not thread safe on Linux?

[David Van Couvering <da...@vancouvering.com>]

Hi, all.  Don't ask me why, but I have a stress test that launches 100
simultaneous threads, all of which grab their own connection pool, and send
a CREATE TABLE command to the same Derby database.  It ignores exceptions
saying the table is already created.

This works find on Windows.  However, on RHEL, I get a lot of nasties - I
get low-level NullPointerException and "operation interrupted" from nio.
Bad news all around.

I then put a global lock around my create table operation, and voila, works.

I don't currently have the time to put together a formal reproduction, but I
thought I should let  you know, perhaps it's something somebody wants to
check out - it's pretty easy to write up the test case.

David

-- 
David W. Van Couvering

http://www.linkedin.com/in/davidvc
http://davidvancouvering.blogspot.com
http://twitter.com/dcouvering

Re: CREATE TABLE not thread safe on Linux?

[David Van Couvering <da...@gmail.com>]

Hm, possibly.  I can try the same thing using DriverManager.getConnection()
instead of a connection pool.

On Fri, Apr 9, 2010 at 1:10 AM, Knut Anders Hatlen <Kn...@sun.com>wrote:

> On 04/ 8/10 09:00 PM, David Van Couvering wrote:
> > Hi, all.  Don't ask me why, but I have a stress test that launches 100
> > simultaneous threads, all of which grab their own connection pool, and
> > send a CREATE TABLE command to the same Derby database.  It ignores
> > exceptions saying the table is already created.
> >
> > This works find on Windows.  However, on RHEL, I get a lot of nasties
> > - I get low-level NullPointerException and "operation interrupted"
> > from nio.  Bad news all around.
>
> Hi David,
>
> Could the problem be that your connection pool is sending interrupts to
> the executing threads? I vaguely recall cases where connection pools
> have been said to do that kind of things.
>
> --
> Knut Anders
>
>


-- 
David W. Van Couvering

http://www.linkedin.com/in/davidvc
http://davidvancouvering.blogspot.com
http://twitter.com/dcouvering

Re: CREATE TABLE not thread safe on Linux?

[Knut Anders Hatlen <Kn...@Sun.COM>]

On 04/ 8/10 09:00 PM, David Van Couvering wrote:
> Hi, all.  Don't ask me why, but I have a stress test that launches 100
> simultaneous threads, all of which grab their own connection pool, and
> send a CREATE TABLE command to the same Derby database.  It ignores
> exceptions saying the table is already created.
>
> This works find on Windows.  However, on RHEL, I get a lot of nasties
> - I get low-level NullPointerException and "operation interrupted"
> from nio.  Bad news all around.

Hi David,

Could the problem be that your connection pool is sending interrupts to
the executing threads? I vaguely recall cases where connection pools
have been said to do that kind of things.

-- 
Knut Anders