Hmmm, the reason i asked this question is regarding to implementation of : CharTermAttribute.
It seems tokenizer will set token read from reader into it, and the following tokenstream can also get this instance. My concern is in a multi-thread envioment. another thread can also change the content of CharTermAttributeImpl. the token is got with this api: char[] buffer = termAtt.buffer(); but, the buffer can be changed by another thread, right? cuz it's the same object. I'm not concern about the create/get object phrase. Thanks, On Sun, Nov 4, 2012 at 2:07 PM, Uwe Schindler <u...@thetaphi.de> wrote: > Hi, > > > I have two confused questions regarding Lucene implementation, hope > > someone can give me some clues. > > > > 1. It's about the AttributeSource/AttributeSourceImpl implemenation. > > Seems like the default instance was kept as "static" > > in DefaultAttributeFactory. But we get these instances in analyzer > directly. In > > this point of view, analyzer implementation is not thread safe, right? > > Because each attributesourceimpl object will refer to same instance but > > without synchronization. > > This is not a problem. Analyzers are threadsafe; every TokenStream > instance is used only in one thread. > The DefaultAttributeFactory singleton is not a problem, as the instance is > only used read-only and all members are final and the internal state of > DefaultAttributeFactory instance does not change. The static cache inside > DefaultAttributeFactory#getClassForInterface is thread safe, as it uses a > concurrent map. The members of the map are Class<? extends AttributeImpl>; > each AttributeImpl is created with newInstance() from the Class<? extends > AttributeImpl> instance. > > Uwe > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: java-user-unsubscr...@lucene.apache.org > For additional commands, e-mail: java-user-h...@lucene.apache.org > >
