[
https://issues.apache.org/jira/browse/LANG-1086?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14337203#comment-14337203
]
Arthur Naseef commented on LANG-1086:
-------------------------------------
Reading the javadocs for the atomic package, compareAndSet is the atomic
operation. There is a lock there, whether it is in java code, machine
instructions or other. Even if it's not called a lock. If no instructions can
pass a point in the code until some event, that's a lock.
Avoiding unstructured locks (i.e. unclear orders-of-operations with lock and
unlock steps) and large critical sections is very valuable in concurrent
implementations. Implementing a concurrency toolset without locks - at some
level - isn't possible. Ultimately, there must be some form of atomic
"check-and-set" which means a lock; it could be a spinlock (busy-wait with a
mostly-guaranteed very short "spin" life), but it still operates as a lock.
In spite of any of this, the existing busy-wait solution is problematic.
Especially if the initialize method throws an exception, leaving other threads
busy-waiting indefinitely.
Oh, and does the LazyInitiaizer get a "pass" on the rules? It's calling the
initializer inside a "synchronized' block.
> Remove busy wait from AtomicSafeInitializer.get()
> -------------------------------------------------
>
> Key: LANG-1086
> URL: https://issues.apache.org/jira/browse/LANG-1086
> Project: Commons Lang
> Issue Type: Improvement
> Components: lang.concurrent.*
> Reporter: Benedikt Ritter
> Assignee: Benedikt Ritter
> Labels: github
> Fix For: 3.4
>
>
> Placeholder ticket for https://github.com/apache/commons-lang/pull/46
> {quote}
> Remove the busy wait from AtomicSafeInitializer.get().
> Also ensure waiting threads do not wait indefinitely after initialize()
> throws an exception, instead throwing the same exception, re-wrapped, for
> each requester.
> Brought the unit tests up to 100% coverage on AtomicSafeInitializer.
> Eliminated race condition on verifying at least one thread waiting for
> initialize() to complete in another thread.
> {quote}
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
