Re: Hashmap and multiple threads
Hoss Spence wrote:
Although not protecting the Hashmap operations is clearly wrong, it
doesn't explain to me why all threads seemed to be in the containsKey
() call. Does anyone have any ideas? This is hard to duplicate (as
I also find it very suspicious that you managed to get 10 threads inside
a single call. That's like winning the super mega lotto. Are you sure
these threads are unsynchronized? It would make more sense if all these
threads were blocked and waiting on the same lock.
Are you sure you have an actual HashMap and not some synchronized
object? The latter would make more sense.
Anyway, Lew's right, multi-threading is tricky and should be studied
carefully before making attempts to "fix" things. Simply using a call like
Map h = Collections.synchronizedMap( new HashMap() );
to create this HashMap will protect your map, but it won't necessarily
protect your code. A strong analysis of the code is probably in order
to determine if there are more serious issues.
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