Hi.
I am having trouble with threading in Ruby.
My code outputs: `synchronize': stopping only thread (ThreadError).
What does this mean and what could the cause of this error be?!
I have a method named p, defined as follows:
@mutex.synchronize do
db_open
yield(@db)
db_close
end
...p gets called with a block which uses db.
Cheers,
Sergio
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I am having trouble with threading in Ruby.
My code outputs: `synchronize': stopping only thread (ThreadError).What does this mean and what could the cause of this error be?!
It means that you have a deadlock situation, where one thread is waiting for a resource that will never be released.
My ruby (1.8.7) gives a slightly different error when I try this but take this example:
mutex = Mutex.new
mutex.synchronize do # (1) lock the mutex
mutex.synchronize do # Wait for the mutex to become available then lock it
puts "hi"
end
end # unlock the mutex locked by (1)
The inner "synchronize" is waiting for the mutex lock, but it will never get it, because the mutex will only get unlocked when the outer synchronize finishes.
I have a method named p, defined as follows:
@mutex.synchronize do
db_open
yield(@db)
db_close
end
If the block you're passing into this method tries to lock the mutex, either directly or by calling synchronize, you'll get deadlock. The block you pass will be trying to lock the mutex, but the mutex is already locked by the 'p' method. By the way, you might not want to call your method 'p' because 'p' is already a well-known, often-used method.
Ben
On Sep 9, 2010, at 09:22, Sergio Lombrico wrote: