Bugs item #2111613, was opened at 2008-09-15 09:33
Message generated for change (Comment added) made by ketamin
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Category: libcurl
Group: hang
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Igor (ketamin)
Assigned to: Daniel Stenberg (bagder)
Summary: multi object is stuck

Initial Comment:
Configuration
-------------
libcurl/7.18.2 OpenSSL/0.9.8h zlib/1.2.3 Windows XP/SP2

Application
-----------
My application is a single-thread client application
that accesses XCAP server in order to manipulate documents
stored on it.
The application uses 'multi' and curl_multi_socket() API
in order to work asynchronously.

Scenario
--------
The application performs following transactions in sequential order:
1. PUT-401-PUT-500 - trial to create doc on server
2. PUT-401-PUT-500 - trial to modify doc on server
3. GET-401-GET-500 - trial to fetch doc from server
4. POST-401-POST-500 - trial to search on server
5. DELETE-401-DELETE-500 - trial to delete doc

All transactions share same 'multi' object.
Each of transactions use dedicated 'easy' object.
Same 'easy' object is used for both original request and
for next authorization retrial request:
on receiving 401 the 'easy' is removed for the 'multi',
the username/password are set into it,
and it is added back to the 'multi' again.

Problem
-------
Sometimes after the 'easy' is added back to the 'multi'
in order to send authorized request nothing happens -> the application is stuck.

Logs

----
To my sorrow the problem doesn't appear when debugging info is printed.
Therefore I added 'printf'-s into the all libcurl API functions/callbacks
used/implemented by the application.
At the begining of the attached file you can see snip of the full log,
where the last good transaction and the next to it bad transaction are logged.
After snip the full log appears.
As it can be seen from the log,
the call to last curl_multi_add_handle() doesn't initiate any activity,
because 'timer_lastcall' is equeal to the 'multi->timetree->key'.
Is there any chance that the millisecond timer resolution is not enough?
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>Comment By: Igor (ketamin)
Date: 2008-09-16 08:03
Message:
Hi Dan,
Thanks for reply!
I'd failed to find something usable in mailing list.
Therefore I would like to submit a patch based on
QueryPerformanceFrequency/QueryPerformanceCounter API. It provides even
nanosecond resolution that should be definitely enough for near future.
Could you address me to some doc that explain the patch submitting
process?
I dug in http://curl.haxx.se/docs/ and in gmane.comp.web.curl.library but
without success. Should I simply post the output of 'diff' to the mailing
list?
One more question. I would like to submit another patch, which separates
username and password options for curl_easy_setopt() in order to enable
colon in username (in order to pass Digest authentication). Should I
provide patch for curl_easy_setopt.pdf, curl_easy_setopt.3 and
curl_easy_setopt.html documentation files also?
Thank you very much in advance,
Igor
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Comment By: Dan Fandrich (dfandrich)
Date: 2008-09-15 19:55
Message:
As I recall, the timer resolution was improved to microsecond resolution in
7.18.2 to prevent problems like this. You may want to bring this problem to
the curl-library mailing list so the Windows developers can suggest a way
to bring microsecond resolution to the Windows port.
----------------------------------------------------------------------
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