0016846: [OCCT Forum] Multithreading troubles: reference counter of Standard_Transient

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Date Submitted

Last Update

0016846

Community

[OCCT] OCCT:Foundation Classes

public

2007-09-05 11:06

2011-12-01 11:22

Reporter

abv

Assigned To

abv

Priority

normal

Severity

trivial

Status

closed

Resolution

fixed

Platform

All

OS Version

Product Version

Target Version

Fixed in Version

[OCCT] 6.2.1

Summary

0016846: [OCCT Forum] Multithreading troubles: reference counter of Standard_Transient

Description

As indicated on OCCT Forum message
http://www.opencascade.org/org/forum/thread_11273, [^] OCCT Handle mechanism is not thread-safe due to the fact that
reference counter is not protected against simultaneous modification by several
threads.

See IFMT 214 for discussion of how this can be fixed

Additional information
and documentation updates

Documentation remark, added by ABV 2007-10-22 15:46:39:

New features:
New static functions IsReentrant() and SetReentrant() are added in Standard
package to query and set flag for reentrant (i.e. thread-safe) mode of
operation of TKernel services (memory manager, handles, exceptions).
Note that by default this mode is Off; it can be activated also by defining
environment variable MMGT_REENTRANT before starting OCCT.
Improvements:
Reference counter in Standard_Transient class (thus all OCCT classes managed by
handles) is protected to be thread-safe. Note that this protection is effective
only on Windows and Linux platforms by the moment, and is active only if
reentrant mode is set (see Standard::IsReentrant()).

Note that this improvement leads to some downgrade of performance of creation
and desctruction of Handle objects (by ~ 2 times when reentrant mode is OFF, ~ 10
times when it is ON), thus it becomes yet more important to avoid creation of
unnecessary Handles in performance-critical parts of the code. For information,
the time of creation and destruction of one Handle measured on P4 3GHz CPU is
around 20 ns in non-reentrant mode and 100 ns in reentrant mode.
Changes:
Some changes have been made in basic OCCT headers:

- Statement "using std;" in Standard_Stream.hxx has been replaced by individual
"using" statements for several types used extensively inside OCCT code. This
should reduce risk of conflicts between OCCT headers and application codes due
to imported STL names. On the other side, some code probably might need to be
corrected to add std:: prefix before STL classes (or equivalent using
statement).

- In Standard_Macro.hxx for WNT plaftform, a number of macros have been defined
(such as WIN32_LEAN_AND_MEAN) aimed to reduce scope of symbols defined by
eventual inclusion of windows.h. This is necessary to prevent interference
between multiple macro definitions made in windows.h (e.g. SendMessage #defined
as SendMessageA) and normal code of OCCT and applications. If some code needs
complete set of symbols defined in windows.h, this code may include windows.h
prior to OCCT headers.

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Attached Files

occ16846-abv-v1.tar.gz (17,199 bytes) 2007-09-05 09:27

occ16846-abv-test-v1.tar.gz (1,626 bytes) 2007-09-05 10:13

occ16846perf.xls (23,552 bytes) 2007-09-05 10:13

occ16846-abv-v2.tar.gz (18,330 bytes) 2007-09-10 11:20

occ16846-abv-v3.tar.gz (21,096 bytes) 2007-09-10 12:50

occ16846-abv-v4.tar.gz (170,111 bytes) 2007-09-26 11:09

occ16846-abv-gal-v1.tar.gz (39,244 bytes) 2007-09-26 11:27

occ16846-abv-v5.tar.gz (175,141 bytes) 2007-09-27 18:08

occ16846-abv-v6.tar.gz (198,489 bytes) 2007-10-02 13:31

occ16846-abv-v7.tar.gz (237,406 bytes) 2007-10-04 14:39

occ16846-prod-abv-v1.tar.gz (5,425 bytes) 2007-10-08 15:48

occ16846-prod-abv-v2.tar.gz (8,862 bytes) 2007-10-08 17:28

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Issue History
Date Modified	Username	Field	Change
2007-09-05 11:28	abv	CC	=> pdn, szv, agv
2007-09-07 16:51	bugmaster	Status	closed => assigned
2007-09-07 16:51	bugmaster	Resolution	suspended => @0@
2007-09-07 16:52	bugmaster	Assigned To	bugmaster => abv
2007-09-10 13:24	abv	Status	assigned => resolved
2007-10-09 17:24	bugmaster	Status	resolved => tested
2007-10-25 18:31	bugmaster	Status	tested => verified
2009-06-23 17:10	bugmaster	Status	verified => closed
2009-06-23 17:10	bugmaster	Resolution	@0@ => fixed
2011-08-02 11:23	bugmaster	Category	OCCT:FDC => OCCT:Foundation Classes
2011-11-28 10:38	abv	Description Updated	View Revisions
2011-11-28 10:38	abv	Additional Information Updated	View Revisions
2011-11-28 10:39	abv	Description Updated	View Revisions
2011-12-01 11:22	szy	Additional Information Updated	View Revisions