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From Keith Massey <>
Subject Re: ScannerIterator thread use
Date Wed, 02 Nov 2011 14:18:17 GMT
On 11/1/11 9:53 PM, Keith Turner wrote:
> On Tue, Nov 1, 2011 at 6:12 PM, Keith Massey
> <>  wrote:
>> I'm not incredibly familiar with this code, but it could be a static thread
>> pool right? And just let all ScannerIterators share some configurable thread
>> pool? The thread would just be returned to the pool when the Reader
>> completed.
> When I think of thread pools, I always think of setting an upper bound
> on the number of threads.  It occurred to me that we could use a
> static thread pool if it were unbounded.  This would replicate the
> current behavior and allow for thread reuse.  So make the core size
> small (0,1 or 2),  the max size MAX_INT, the timeout small (few
> seconds), and use a SynchronousQueue.  Everything added to the pool
> should create a new thread if one is not available.  Also make the
> threads daemon threads so they do not keep the process alive.

I think that would actually be much better than replicating the current 
behavior -- most of those threads seem to be very short-lived and we 
seem to get into trouble because the garbage collector is not reclaiming 
them fast enough (and I'm guessing we're bumping up against our ulimit). 
An unbounded pool would probably stay relatively small in most cases. 
Having the option of passing in a bounded thread pool would be nice 
though. If we have hundreds of users querying accumulo at once we'll 
probably need some way to bound the number of threads so we don't crash 
our server (although I guess we could do that in our code that calls 

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