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Minor improvements to the threading introduction: 

* Expand the example to show a join.

* Mention the use case of I/O running concurrent with a computational
  thread.

* Be a tad more forceful about recommending Queue over other approaches
  to synchonization.

* Eliminate discussion around having a single interpreter.  This is a
  more advanced discussion that belongs in the library reference and
  in a section on extending and embedding.
This commit is contained in:
Raymond Hettinger 2004-08-16 05:11:04 +00:00
parent 84f107dd15
commit d3fe2395b4
1 changed files with 15 additions and 11 deletions
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26
Doc/tut/tut.tex
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@ -4868,12 +4868,12 @@ numbers respectively):
\section{Multi-threading\label{multi-threading}}
Threading is a technique for decoupling tasks which are not sequentially
dependent. Python threads are driven by the operating system and run
in a single process and share memory space in a single interpreter.
dependent. Threads can be used to improve the responsiveness of
applications that accept user input while other tasks run in the
background. A related use case is running I/O in parallel with
computations in another thread.
Threads can be used to improve the responsiveness of applications that
accept user input while other tasks run in the background. The
following code shows how the high level
The following code shows how the high level
\ulink{\module{threading}}{../lib/module-threading.html} module can run
tasks in background while the main program continues to run:
@ -4891,8 +4891,12 @@ tasks in background while the main program continues to run:
f.close()
print 'Finished background zip of: ', self.infile
AsyncZip('mydata.txt', 'myarchive.zip').start()
print 'The main program continues to run'
background = AsyncZip('mydata.txt', 'myarchive.zip')
background.start()
print 'The main program continues to run in foreground.'
background.join() # Wait for the background task to finish
print 'Main program waited until background was done.'
\end{verbatim}
The principal challenge of multi-threaded applications is coordinating
@ -4901,13 +4905,13 @@ module provides a number of synchronization primitives including locks,
events, condition variables, and semaphores.
While those tools are powerful, minor design errors can result in
problems that are difficult to reproduce. A simpler and more robust
approach to task coordination is concentrating all access to a resource
problems that are difficult to reproduce. So, the preferred approach
to task coordination is to concentrate all access to a resource
in a single thread and then using the
\ulink{\module{Queue}}{../lib/module-Queue.html} module to feed that
thread with requests from other threads. Applications that use
thread with requests from other threads. Applications using
\class{Queue} objects for inter-thread communication and coordination
tend to be easier to design, more readable, and more reliable.
are easier to design, more readable, and more reliable.
\section{Logging\label{logging}}