For what its worth... That is not my understanding. My understanding is that volatile just ensures the JIT always accesses the var in order - prevents some compiler optimizations - where as synchronized needs to acquire the lock. (There were discussions regarding having volatile create synchronized accessors behind the scenes - but I don't think that semantic was ever agreed upon).
That coupled with using primitives (to avoid the early memory alloc - since primitives are allocated on the stack), allows the double-locked synchronization to work (at least that is my understanding). -----Original Message----- From: Chris Hostetter [mailto:[EMAIL PROTECTED] Sent: Wednesday, May 10, 2006 12:51 AM To: Lucene Dev Subject: RE: Multiple threads searching in Lucene and the synchronized issue. -- solution attached. : I think you could use a volatile primitive boolean to control whether or not : the index needs to be read, and also mark the index data volatile and it : SHOULD PROBABLY work. : : But as stated, I don't think the performance difference is worth it. My understanding is: 1) volatile will only help as of java 1.5 ... lucene targets 1.4 compatibility. 2) in 1.5, volatile is basically just as expensive as synchronized. : I met these problem before indeed.The compiler did something optimized for : me that was bad for me when I see the byte-codes. : When I'm using a function local variable, m_indexTerms and in JDK1.5.06, it : seems ok. : Whether it will break in other environments, I still don't know about it. The dangerous thing is that even if the byte code looks okay, and if it works okay today, your app could run for a while and then all of the sudden it could stop working because of the order the threads are run, or becuase of an optimization the JVM applies on the fly. -Hoss --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
