You are viewing a plain text version of this content. The canonical link for it is here.
Posted to derby-dev@db.apache.org by "Knut Anders Hatlen (Created) (JIRA)" <ji...@apache.org> on 2012/02/20 09:55:36 UTC
[jira] [Created] (DERBY-5623) Loosen up synchronization in
FileMonitor
Loosen up synchronization in FileMonitor
----------------------------------------
Key: DERBY-5623
URL: https://issues.apache.org/jira/browse/DERBY-5623
Project: Derby
Issue Type: Improvement
Components: Services
Affects Versions: 10.8.2.2
Reporter: Knut Anders Hatlen
When opening a large number of databases in parallel, many threads get stuck for a long time in FileMonitor, as reported in this thread on derby-user:
http://mail-archives.apache.org/mod_mbox/db-derby-user/201202.mbox/%3CCAEQ8c00vx0yFrwWyjm%3Dt_Yd%2BuuKGOL%3DSgpYfQuYghOOPgdN8-w%40mail.gmail.com%3E
The synchronization in FileMonitor is only needed because the monitor instance is also used as a shared PrivilegedExceptionAction instance. Since all databases share one FileMonitor instance, threads that access any of these methods are serialized. If each method created its own PrivilegedAction or PrivilegedExceptionAction instance instead of using the monitor's run() method, these methods wouldn't need synchronization.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Resolved] (DERBY-5623) Loosen up synchronization in
FileMonitor
Posted by "Knut Anders Hatlen (Resolved) (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/DERBY-5623?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Knut Anders Hatlen resolved DERBY-5623.
---------------------------------------
Resolution: Fixed
Fix Version/s: 10.9.0.0
Assignee: Knut Anders Hatlen
I committed the patch with revision 1292724. Marking the issue as resolved.
> Loosen up synchronization in FileMonitor
> ----------------------------------------
>
> Key: DERBY-5623
> URL: https://issues.apache.org/jira/browse/DERBY-5623
> Project: Derby
> Issue Type: Improvement
> Components: Services
> Affects Versions: 10.8.2.2
> Reporter: Knut Anders Hatlen
> Assignee: Knut Anders Hatlen
> Fix For: 10.9.0.0
>
> Attachments: d5623-1.diff, derby-diff.txt
>
>
> When opening a large number of databases in parallel, many threads get stuck for a long time in FileMonitor, as reported in this thread on derby-user:
> http://mail-archives.apache.org/mod_mbox/db-derby-user/201202.mbox/%3CCAEQ8c00vx0yFrwWyjm%3Dt_Yd%2BuuKGOL%3DSgpYfQuYghOOPgdN8-w%40mail.gmail.com%3E
> The synchronization in FileMonitor is only needed because the monitor instance is also used as a shared PrivilegedExceptionAction instance. Since all databases share one FileMonitor instance, threads that access any of these methods are serialized. If each method created its own PrivilegedAction or PrivilegedExceptionAction instance instead of using the monitor's run() method, these methods wouldn't need synchronization.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Commented] (DERBY-5623) Loosen up synchronization in
FileMonitor
Posted by "David Sitsky (Commented) (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/DERBY-5623?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13212968#comment-13212968 ]
David Sitsky commented on DERBY-5623:
-------------------------------------
Great - sounds good.
> Loosen up synchronization in FileMonitor
> ----------------------------------------
>
> Key: DERBY-5623
> URL: https://issues.apache.org/jira/browse/DERBY-5623
> Project: Derby
> Issue Type: Improvement
> Components: Services
> Affects Versions: 10.8.2.2
> Reporter: Knut Anders Hatlen
> Attachments: d5623-1.diff, derby-diff.txt
>
>
> When opening a large number of databases in parallel, many threads get stuck for a long time in FileMonitor, as reported in this thread on derby-user:
> http://mail-archives.apache.org/mod_mbox/db-derby-user/201202.mbox/%3CCAEQ8c00vx0yFrwWyjm%3Dt_Yd%2BuuKGOL%3DSgpYfQuYghOOPgdN8-w%40mail.gmail.com%3E
> The synchronization in FileMonitor is only needed because the monitor instance is also used as a shared PrivilegedExceptionAction instance. Since all databases share one FileMonitor instance, threads that access any of these methods are serialized. If each method created its own PrivilegedAction or PrivilegedExceptionAction instance instead of using the monitor's run() method, these methods wouldn't need synchronization.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Updated] (DERBY-5623) Loosen up synchronization in
FileMonitor
Posted by "Knut Anders Hatlen (Updated) (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/DERBY-5623?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Knut Anders Hatlen updated DERBY-5623:
--------------------------------------
Attachment: d5623-1.diff
Thanks for the patch, David. I had played with a similar patch myself (see the attached file, d5623-1.diff). My patch differs a little from your patch:
- It preserves the synchronization in getDaemonThread(). Without synchronization in that method, I saw occasional IllegalThreadStateExceptions when booting and shutting down databases concurrently in many threads.
- It uses PrivilegedAction instead of PrivilegedExceptionAction for the actions that don't throw checked exceptions, which made the exception handling simpler.
All the regression tests passed with this patch.
I also ran an application that booted 1000 databases in 20 threads on a machine with 8 cores, and the patch seemed to speed it up by 3-4%. It was primarily the removal of synchronization in getJVMProperty() that contributed to the speed-up.
Although the speed-up is modest (at least in my environment) the patches remove more lines of code than they add, which is a good thing in itself.
> Loosen up synchronization in FileMonitor
> ----------------------------------------
>
> Key: DERBY-5623
> URL: https://issues.apache.org/jira/browse/DERBY-5623
> Project: Derby
> Issue Type: Improvement
> Components: Services
> Affects Versions: 10.8.2.2
> Reporter: Knut Anders Hatlen
> Attachments: d5623-1.diff, derby-diff.txt
>
>
> When opening a large number of databases in parallel, many threads get stuck for a long time in FileMonitor, as reported in this thread on derby-user:
> http://mail-archives.apache.org/mod_mbox/db-derby-user/201202.mbox/%3CCAEQ8c00vx0yFrwWyjm%3Dt_Yd%2BuuKGOL%3DSgpYfQuYghOOPgdN8-w%40mail.gmail.com%3E
> The synchronization in FileMonitor is only needed because the monitor instance is also used as a shared PrivilegedExceptionAction instance. Since all databases share one FileMonitor instance, threads that access any of these methods are serialized. If each method created its own PrivilegedAction or PrivilegedExceptionAction instance instead of using the monitor's run() method, these methods wouldn't need synchronization.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Updated] (DERBY-5623) Loosen up synchronization in
FileMonitor
Posted by "David Sitsky (Updated) (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/DERBY-5623?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
David Sitsky updated DERBY-5623:
--------------------------------
Attachment: derby-diff.txt
Patch file to remove synchronisation in FileMonitor.
> Loosen up synchronization in FileMonitor
> ----------------------------------------
>
> Key: DERBY-5623
> URL: https://issues.apache.org/jira/browse/DERBY-5623
> Project: Derby
> Issue Type: Improvement
> Components: Services
> Affects Versions: 10.8.2.2
> Reporter: Knut Anders Hatlen
> Attachments: derby-diff.txt
>
>
> When opening a large number of databases in parallel, many threads get stuck for a long time in FileMonitor, as reported in this thread on derby-user:
> http://mail-archives.apache.org/mod_mbox/db-derby-user/201202.mbox/%3CCAEQ8c00vx0yFrwWyjm%3Dt_Yd%2BuuKGOL%3DSgpYfQuYghOOPgdN8-w%40mail.gmail.com%3E
> The synchronization in FileMonitor is only needed because the monitor instance is also used as a shared PrivilegedExceptionAction instance. Since all databases share one FileMonitor instance, threads that access any of these methods are serialized. If each method created its own PrivilegedAction or PrivilegedExceptionAction instance instead of using the monitor's run() method, these methods wouldn't need synchronization.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira