| msg177874 - (view) |
Author: Trent Nelson (trent) *  |
Date: 2012-12-21 10:39 |
| Relevant thread: http://mail.python.org/pipermail/python-dev/2012-December/123225.html PyOS_StdioReadline features numerous calls that require the GIL to be held. Ideally, the GIL drop-take should be moved closer to the actual underlying read system call. |
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| msg188397 - (view) |
Author: Antoine Pitrou (pitrou) * |
Date: 2013-05-04 18:51 |
| So, could you propose a patch? |
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| msg188499 - (view) |
Author: Kristján Valur Jónsson (kristjan.jonsson) * |
Date: 2013-05-06 09:35 |
| My quick and dirty fix is simple: _PyOS_ReadlineTState = PyThreadState_GET(); /* CCP change, cannot release the GIL here because PyOS_StdioReadline uses * the regular MALLOC */ /* Py_BEGIN_ALLOW_THREADS */ #ifdef WITH_THREAD PyThread_acquire_lock(_PyOS_ReadlineLock, 1); #endif /* This is needed to handle the unlikely case that the * interpreter is in interactive mode *and* stdin/out are not * a tty. This can happen, for example if python is run like * this: python -i < test1.py */ if (!isatty (fileno (sys_stdin)) | |
!isatty (fileno (sys_stdout))) rv = PyOS_StdioReadline (sys_stdin, sys_stdout, prompt); else rv = (*PyOS_ReadlineFunctionPointer)(sys_stdin, sys_stdout, prompt); /* Py_END_ALLOW_THREADS */ #ifdef WITH_THREAD PyThread_release_lock(_PyOS_ReadlineLock); #endif Basically, we just comment out the lock release since we don't need it. The reason we found this was that we were using GIL a custom mallocator which should have been run with the GIL but wasn´t. |
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| msg191092 - (view) |
Author: STINNER Victor (vstinner) * |
Date: 2013-06-13 21:22 |
| I just found the readline/GIL issue while working on #18203. I created #18205 but then I found this issue. I just closed #18205 as a duplicate. Here is a patch for Python 3.4. -- Copy of the initial message (): The callback PyOS_ReadlineFunctionPointer (used to read a line from the standard input) must return a buffer allocated by PyMem_Malloc(), but PyOS_Readline() releases the GIL before calling PyOS_ReadlineFunctionPointer. Simplified extract of PyOS_Readline(): Py_BEGIN_ALLOW_THREADS if (!isatty (fileno (sys_stdin)) | |
!isatty (fileno (sys_stdout))) rv = PyOS_StdioReadline (sys_stdin, sys_stdout, prompt); else rv = (*PyOS_ReadlineFunctionPointer)(sys_stdin, sys_stdout, prompt); Py_END_ALLOW_THREADS tok_nextc() calls PyOS_Readline() and calls PyMem_FREE() to release its result. PyOS_ReadlineFunctionPointer should allocate memory using malloc(), not using PyMem_Malloc(). But PyOS_Readline() should copy the line into a buffer allocated by PyMem_Malloc() to keep backward compatibility. See also issue #18203 and #3329. |
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| msg191094 - (view) |
Author: STINNER Victor (vstinner) * |
Date: 2013-06-13 22:10 |
| See the following thread on python-dev, the root problem is that PyMem_Malloc() cannot be called with the GIL held. This is a bug in my opinion, and it should be fixed. http://mail.python.org/pipermail/python-dev/2013-June/126822.html |
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| msg191178 - (view) |
Author: STINNER Victor (vstinner) * |
Date: 2013-06-15 00:35 |
| Updated patch for the final API of #3329. Update also the documentation. PyOS_ReadlineFunctionPointer must now use PyMem_RawMalloc() or PyMem_RawRealloc(), instead of PyMem_Malloc() or PyMem_Realloc(). |
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| msg199388 - (view) |
Author: Roundup Robot (python-dev)  |
Date: 2013-10-10 14:19 |
| New changeset 98dbe677dfe7 by Victor Stinner in branch 'default': Close #16742: Fix misuse of memory allocations in PyOS_Readline() http://hg.python.org/cpython/rev/98dbe677dfe7 |
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| msg200340 - (view) |
Author: Roundup Robot (python-dev) |
Date: 2013-10-19 00:40 |
| New changeset 6c9050ad1afc by Victor Stinner in branch 'default': Issue #16742: My fix on PyOS_StdioReadline() was incomplete, PyMem_FREE() was http://hg.python.org/cpython/rev/6c9050ad1afc |
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| msg200390 - (view) |
Author: Kristján Valur Jónsson (kristjan.jonsson) * |
Date: 2013-10-19 09:48 |
| Perhaps in debug builds the memory apis should verify consistency and matching useage. |
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| msg200404 - (view) |
Author: STINNER Victor (vstinner) * |
Date: 2013-10-19 11:34 |
| > Kristján Valur Jónsson added the comment: > > Perhaps in debug builds the memory apis should verify consistency and matching useage. Python does check usage of apis in debug mode. Memory allocation failure are almost never checked. See my pyfailmalloc module for that. |
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