Issue1370

classification
Title: Use System.identityHashCode for id()
Type: rfe Severity: normal
Components: Core Versions:
process
Status: closed Resolution: wont fix
Dependencies: Superseder:
Assigned To: Nosy List: pedronis, pjenvey
Priority: low Keywords:

Created on 2009-06-07.23:33:25 by pjenvey, last changed 2009-08-19.01:48:41 by pjenvey.

Messages
msg4804 (view) Author: Philip Jenvey (pjenvey) Date: 2009-06-07.23:33:24
In olden times we decided to create our own id()s rumor has it due to 
heavy usage of System.identityHashCode affecting performance

I suspect that's no longer the case on modern day JVMs (but we'd need to 
confirm that). Using systemIdentityHash code would simplify our silly id 
implementation and ease debugging when using Java debugger/profiler 
tools
msg4805 (view) Author: Philip Jenvey (pjenvey) Date: 2009-06-07.23:44:04
I thought that was the reason anyway, I'm not so sure from the commit 
message of:

http://fisheye3.atlassian.com/changelog/jython/?cs=2343
msg4806 (view) Author: Philip Jenvey (pjenvey) Date: 2009-06-08.00:05:20
Note that regrtest passes just fine w/ identityHashCode (quickest way to 
try is have IdImpl.java_obj_id call it)
msg4900 (view) Author: Philip Jenvey (pjenvey) Date: 2009-07-15.01:32:21
pedronis mentions the reason for it here 
http://markmail.org/message/fiuxxvjkdqhdtd4e#query:+page:1+mid:cmnq44kzu
b43vvdr+state:results

but I don't understand. He says it was because our Java wrappers weren't 
unique. They were being recycled?
msg4903 (view) Author: Samuele Pedroni (pedronis) Date: 2009-07-15.09:12:47
on a moving gc the identity hash is not unique, id() needs to be unique.
So not using it is a matter of correctness not speed.

But this issue is too terse for me to be sure what is talking about.
msg5057 (view) Author: Philip Jenvey (pjenvey) Date: 2009-08-19.01:48:40
That's the answer I was looking for, thanks Samuele
History
Date User Action Args
2009-08-19 01:48:41pjenveysetstatus: open -> closed
resolution: wont fix
messages: + msg5057
2009-07-15 09:12:47pedronissetmessages: + msg4903
2009-07-15 01:32:22pjenveysetmessages: + msg4900
2009-06-08 00:05:20pjenveysetmessages: + msg4806
2009-06-07 23:44:04pjenveysetnosy: + pedronis
messages: + msg4805
2009-06-07 23:33:25pjenveycreate