[jbossts-issues] [JBoss JIRA] (JBTM-2949) Remove synchronization from ThreadUtil.getThreadId

[Michael Musgrove (JIRA)]

    [ https://issues.jboss.org/browse/JBTM-2949?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13482961#comment-13482961 ] 

Michael Musgrove commented on JBTM-2949:
----------------------------------------

I have taken a look back at older version of the code and we have already had four goes at implementing this (although we haven't tried Luis's approach):

Fix 1: removeChildThread(Thread.currentThread().getName());

Fix 2 (JBOSSTS_4_2_2_GA): final String threadId = Integer.toHexString(System.identityHashCode(t)) ;

Fix 3 (JBOSSTS_4_2_3_GA):_childThreads.put(ThreadUtil.getThreadId(t), t);

Fix 4: the one that Tom did in the 5 stream.

Clearly there is a history of getting this wrong and I would prefer not to try a new implementation without being able to quantify the benefit (I am not say there is no benefit but we need to see the numbers).

> Remove synchronization from ThreadUtil.getThreadId
> --------------------------------------------------
>
>                 Key: JBTM-2949
>                 URL: https://issues.jboss.org/browse/JBTM-2949
>             Project: JBoss Transaction Manager
>          Issue Type: Enhancement
>            Reporter: Luis Barreiro
>
> JBTM-2808 adds synchronization on {{ThreadUtil.getThreadId()}} but that solution does not scale well enough under high contention. 
> There seems to be ways to remove this synchronization:
> # *ConcurrentWeakHashMap* - replace the current {{WeakHashMap}} for a similar data structure that can handle concurrent access. This keeps the same behavior.
> # *Use Thread.getId()* - remove all mappings and generate the {{threadId}} from the {{Thread}}. Although the javadoc mentions that IDs can be reused, the implementation is a counter, like what {{ThreadUtil}} has now. This is the simplest and most elegant fix.
> # *Remove {{threadId}}* - remove the generation of {{threadId}} and use the {{Thread}} throughout the code, generating string IDs when necessary. Probably yields the best performance, but requires the most changes.



--
This message was sent by Atlassian JIRA
(v7.5.0#75005)