[gambit-list] Thread question
feeley at iro.umontreal.ca
Mon Oct 5 08:54:47 EDT 2009
On 5-Oct-09, at 12:50 AM, Mikael More wrote:
> Dear Marc,
> May threads be GC:ed in case they are started, but there's no
> variable references to them?
> I.e., might (##gc) after having evaluated
> (thread-start! (make-thread (lambda () (let loop () (print ".")
> (thread-sleep! 0.5) (loop)))))
> stop the thread?
No. The run queue managed by the thread scheduler is part of the root
set. The timeout queue, which is used by thread-sleep! and other
operations with a timeout, is also part of the root set. So if a
thread is "runnable" or it might wake up after a timeout period has
elapsed, then it will not be collected.
Unreachable blocked threads *can* be garbage collected (for example a
thread blocked on a mutex that is unreachable). I tried writing a
program which exhibits this behavior but couldn't, so I suspect there
is a spurious reference to the thread and I need some time to track
> For a side question, the documentation says "The thread’s execution
> consists of a call to thunk with the initial continuation. This
> continuation causes the (then) current thread to store the result in
> its end-result field, abandon all mutexes it owns, and finally
> terminate.". By end-result, do you mean that the return value of the
> thread thunk is stored somehow in the thread variable?
Yes. If the result terminated normally, the result is accessible with
the thread-join! procedure.
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