Title: Jython $py.class bytecode doesn't include the .py's mtime
Type: behaviour Severity: normal
Components: Core Versions:
Status: closed Resolution: fixed
Dependencies: Superseder:
Assigned To: fwierzbicki Nosy List: cgroves, fwierzbicki, pjenvey, zyasoft
Priority: normal Keywords: test failure causes

Created on 2008-04-17.06:04:28 by pjenvey, last changed 2009-03-06.04:16:19 by fwierzbicki.

msg3157 (view) Author: Philip Jenvey (pjenvey) Date: 2008-04-17.06:04:27
CPython .pyc files include the modified time of the .py file it was 
created from. CPython then knows that the .pyc is up to date by 
comparing the .py's mtime against the .pyc's stored value

Jython doesn't store this value in $py.class, all it does is compare the 
$py.class's mtime against .py on the filesystem

This doesn't seem like a big deal but it makes us incompatible with 

I ran into a situation where this caused a hard to diagnose problem: a 
test would generate a file and invoke a separate process to 
import it. Then it would copy a different version of the same 
file over, and invoke another process that imported it.

The first $py.class generated actually ended up having the same mtime as 
the second .py that was copied over. Because we only compare the mtimes 
of the files themselves, Jython assumed the bytecode was up to date when 
it wasn't, the second .py wasn't compiled/used (causing a very weird 

In this situation in CPython, the first .pyc might have the same mtime 
as the second .py, like our situation above in Jython, but CPython would 
actually be comparing the second .py's mtime against the mtime of the 
first .py, which in this situation were reliably different.

We need to work this way too to avoid surprises like this with code 
written for CPython
msg3158 (view) Author: Charlie Groves (cgroves) Date: 2008-04-17.20:33:37
Issue #1567212 reports the same underlying issue, though it could use a
better title
msg3159 (view) Author: Philip Jenvey (pjenvey) Date: 2008-04-17.20:45:26
dupe of #1567212
msg3549 (view) Author: Jim Baker (zyasoft) Date: 2008-09-13.23:10:45
Assigned to myself to fix in org.python.compiler.ClassFile#write and
corresponding org.python.core.imp#readCode
msg4177 (view) Author: Frank Wierzbicki (fwierzbicki) Date: 2009-03-06.04:16:18
fixed in r6071
Date User Action Args
2009-03-06 04:16:19fwierzbickisetstatus: open -> closed
resolution: duplicate -> fixed
messages: + msg4177
2009-03-03 20:37:18fwierzbickisetassignee: zyasoft -> fwierzbicki
nosy: + fwierzbicki
2008-09-13 23:10:45zyasoftsetstatus: closed -> open
assignee: zyasoft
messages: + msg3549
nosy: + zyasoft
2008-04-17 20:45:27pjenveysetstatus: open -> closed
resolution: duplicate
messages: + msg3159
priority: normal
2008-04-17 20:33:37cgrovessetnosy: + cgroves
messages: + msg3158
2008-04-17 06:04:28pjenveycreate