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From: sstreep@next.com (Sam Streeper)
Newsgroups: comp.sys.next,comp.os.mach
Subject: Re: NXPing() in a thread
Message-ID: <414@rosie.NeXT.COM>
Date: 26 Mar 91 19:41:30 GMT
References: <00946246.F502A0C0@uno.edu> <19044@milton.u.washington.edu>
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In article <19044@milton.u.washington.edu> wiml@milton.u.washington.edu (William Lewis) writes:
>In article <00946246.F502A0C0@uno.edu> jrscs@uno.edu writes:
>>   I have a question on the use of NXPing() in a detached thread.  The
>>detached thread processes some sound data while the "main" thread handles
>>the user interface.  NXPing() works fine inside the main thread but it
>>hangs my NeXT if it call it inside the method for which the thread was
>>launched. 
>
>   I can't imagine how it would hang the whole NeXT, but I can see how
>it could hang your application without much trouble. The trouble

Remember every app is a client of the Window Server.  If you violate
the window server by entering from multiple threads, everybody loses.

>multi-threaded environment. So when you call NXPing() in a subsidiary
>thread, the main thread is probably sitting in DPSGetEvent() (assuming
>it's a normal Appkit-using application), and both threads attempt to
>interact with the window server simultaneously, with undesirable results.

Exactly.

>As far as I
>know, the only way to do this is to send a Mach message to a port
>registered via DPSAddPort(), which will wake up the main thread; the
>handler on that port can then NXPing() or do other arbitrary

This is a good solution.  For a code example similar to this, see
/NextDeveloper/Examples/SortingInAction


-sam
Opinions are not those of my employer.  They're not even mine.  They're
probably wrong besides.  How did they get in here, anyway?

-- 
Opinions are not those of my employer.  They're not even mine.  They're
probably wrong besides.  How did they get in here, anyway?