Re: [Pyunit-interest] PyUnit hangs when I do the following absurdly complicated thing
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Re: [Pyunit-interest] PyUnit hangs when I do the following absurdly complicated thing
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From: Steve P. <ste...@ya...> - 2004-06-30 11:05:38
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Pat,
Without trying it out for myself, I'm pretty sure your problem lies in the=
=20
'displayOuts ' static method, and the fact that you are trying to read the=
=20
child process' stdout fully before moving on to reading its stderr.
When the child process produces output, it goes into a buffer that, when=20
full, must be read (emptied) by the parent process before the child can=20
continue to execute.
The result of read()-ing from stdout is only '-1' if the child process will=
=20
certainly produce no more output on that stream, ie. the child process has=
=20
exited.
What is happening, I think, is that the stderr buffer is filling up with a=
=20
large stack-trace, and the child process will not continue and exit until=20
that has been read. So, reading from stdout blocks the parent process until=
=20
stderr has been read. Note that when a test passes, the volume of stderr=20
output is much less, so you do not see the blocking behaviour in that case.
The correct way to read both output streams of the child process is to copy=
=20
them to System.out in parallel threads, ie. change the first loop to:
InputStream in =3D child.getInputStream();
Thread t =3D new Thread() {
public void run() {
try {
int c;
while ((c =3D in.read()) !=3D -1) {
System.out.print((char)c);
}
in.close();
} catch ( IOException e ) {
throw new RuntimeException(e);
}
}
};
t.start();
then, after reading stderr as before, do
t.join();
Best wishes,
=2DSteve
On Tuesday 29 June 2004 21:51, Pat McGee wrote:
> When I call a PyUnit program from a Java program on Windows XP, and the
> PyUnit program trips an assertion, the Python program hangs. I don't
> know what to try next. Anyone have any suggestions for how I could
> learn more?
>
> I wrote a short Java program (attachment 1) that uses Runtime to run a
> Python program. The specific call is:
> Process child =3D Runtime.getRuntime().exec ("python TripAssert.py",
> null, workDir);
>
> The Python program (attachment 2) imports unittest and then creates a
> test case. The test case has a single line, which is an assert.
>
> When I run the Python program from the command line, it always works,
> whether the assert is true or false. In either case, I get what I
> expect.
>
> When I run the Java program that runs the Python program, it will run
> correctly if the assert is true (sample output 1). But, when the assert
> is false, the program hangs (sample output 2). Sample output 3 shows
> the output when the assert is false and the Python program is run
> directly.
>
> I thought it might be running out of memory. I=92ve got 256 Mb. But, the
> Task Manager says there=92s over 100 Mb available.
>
> I=92m pretty new to Windows programming (I=92m an old Unix programmer), a=
nd
> I don=92t know how to figure out what=92s happening. What tools might I u=
se
> to try to find this? How can I find out what a process is waiting on?
> Anyone seen anything like this?
> Versions:
> =95Python 2.3
> =95PyUnit 1.4.1
> =95Java j2sdk1.4.2_04
> =95Windows XP Pro Version 5.1, Service Pack 1
> --- Attachment 1: Java program -------
> import java.io.File;
> import java.io.InputStream;
>
> public class TestCallPython {
>
> public static void main(String[] args) throws Exception {
> System.out.println ("TestCallPython\n");
> File workDir =3D new File ("\\Documents and settings\\a0868072\\my
> documents\\work\\workspace\\TestCallPython");
> Process child =3D Runtime.getRuntime().exec ("python TripAssert.py",
> null, workDir);
>
> displayOuts (child);
> }
>
> public static void displayOuts (Process child) throws Exception {
> System.out.println ("stdout");
> InputStream in =3D child.getInputStream();
> int c;
> while ((c =3D in.read()) !=3D -1) {
> System.out.print((char)c);
> }
> in.close();
> System.out.println ("\nstderr");
>
> InputStream er =3D child.getErrorStream();
> while ((c =3D er.read()) !=3D -1) {
> System.out.print((char)c);
> }
> er.close();
> System.out.println ("end");
> }
> }
> --- Attachment 2: Python program -------
> import unittest
>
> class LoggingTestCase (unittest.TestCase):
> def test1Assert1 (self):
> #self.assertEqual (1, 2)
> self.assertEqual (1, 1)
>
>
> suite =3D unittest.makeSuite(LoggingTestCase,'test')
>
> if __name__ =3D=3D "__main__":
> unittest.main()
>
> --- Sample output 1: when assertEqual (1, 1) compiled in -------
> C:\Documents and Settings\a0868072\My
> Documents\work\workspace\TestCallPython>java TestCallPython
> TestCallPython
>
> stdout
>
> stderr
> .
> ----------------------------------------------------------------------
> Ran 1 test in 0.000s
>
> OK
> end
>
> C:\Documents and Settings\a0868072\My
> Documents\work\workspace\TestCallPython>
>
> --- Sample output 2: when assertEqual (1, 2) compiled in, from Java
> -------
> C:\Documents and Settings\a0868072\My
> Documents\work\workspace\TestCallPython>java TestCallPython
> TestCallPython
>
> stdout
>
> {Note: I waited about 10 seconds, then hit ^C here.}
> C:\Documents and Settings\a0868072\My
> Documents\work\workspace\TestCallPython>
>
> --- Sample output 3: when assertEqual (1, 2) compiled in, from Python
> -------
> C:\Documents and Settings\a0868072\My
> Documents\work\workspace\TestCallPython>python TripAssert.py
> F
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> FAIL: test1Assert1 (__main__.LoggingTestCase)
> ----------------------------------------------------------------------
> Traceback (most recent call last):
> File "TripAssert.py", line 5, in test1Assert1
> self.assertEqual (1, 2)
> File "c:\python23\lib\unittest.py", line 302, in failUnlessEqual
> raise self.failureException, \
> AssertionError: 1 !=3D 2
>
> ----------------------------------------------------------------------
> Ran 1 test in 0.000s
>
> FAILED (failures=3D1)
>
> C:\Documents and Settings\a0868072\My
> Documents\work\workspace\TestCallPython>
>
> ---
> Pat McGee
> Ph.D. Student, Computer Sciences Department, Florida Institute of
> Technology
> Treasurer, Association for Software Testing, Inc.
> (http://AssociationForSoftwareTesting.org)
> Editor, CS Department Tech Report Library (http://cs.fit.edu/~tr)
>
> jpm...@cs...
> http://blackbox.cs.fit.edu/blog/pat
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