[Tcl-bugs] [ tcl-Bugs-1593707 ] win32 error during simultaneous file open for read

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Bugs item #1593707, was opened at 2006-11-09 11:35
Message generated for change (Comment added) made by melbardis
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>Category: 48. Threading
Group: None
Status: Open
Resolution: None
>Priority: 8
Private: No
Submitted By: eric melbardis (melbardis)
Assigned to: Vince Darley (vincentdarley)
Summary: win32 error during simultaneous file open for read

Initial Comment:
If threads in a multi threaded application (or simply 
multiple copies of a tclsh) try to open the same file 
for reading, there appears to be a window of 
opportunity for windows to return an error, typically 
a ERROR_SHARING_VIOLATION error.

Additionally (in another of my applications non-tcl) 
i found that is a thread closes a file and another 
thread trys to delete the file, the same window can 
apply.

I have modfied win/tclWinChan.c (8.54a, though same 
code seems to exist everywhere...) as follows:

    /*
     * Now we get to create the file.
     */
    {
        //EPM - windows can screwup when opening same 
file at same time
        int retry = 5;
        int err;
        while (retry--) {
            handle = (*tclWinProcs->createFileProc)
(nativeName, accessMode,
                                                    
shareMode, NULL, createMode, flags, (HANDLE) NULL);
            if (handle != INVALID_HANDLE_VALUE) {
                break;
            }
            err = GetLastError();
            if (err == ERROR_FILE_NOT_FOUND) {
                    // File removed by external 
circumstances.
                    break;
            }
            Sleep(100);
            //printf("retry... %d\n", retry);
        }
    }


if the retry message is uncommented, then the retry 
was output occasionally when running the test code, 
with a retry value of 4

note: my machine is a dual-core pentium 2.8 gig




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>Comment By: eric melbardis (melbardis)
Date: 2007-07-18 14:38

Message:
Logged In: YES 
user_id=788816
Originator: YES

no response when filed under the previous category!

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You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=110894&aid=1593707&group_id=10894