Mercurial > cpython-lru_cache-weakref

diff Python/pystate.c @ 44832:eb2eafda29b7 legacy-trunk

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Provide a sanity check during PyThreadState_DeleteCurrent() and PyThreadState_Delete() to avoid an infinite loop when the tstate list is messed up and has somehow becomes circular and does not contain the current thread. I don't know how this happens but it does, *very* rarely. On more than one hardware platform. I have not been able to reproduce it manually. Attaching to a process where its happening: it has always been in an infinite loop over a single element tstate list that is not the tstate we're looking to delete. It has been in t_bootstrap()'s call to PyThreadState_DeleteCurrent() as a pthread is exiting.
author Gregory P. Smith <greg@mad-scientist.com>
date Mon, 21 Jan 2008 07:11:11 +0000
parents 45ce388ec59a
children a8a8232cb541
line wrap: on
line diff
--- a/Python/pystate.c	Sun Jan 20 21:10:08 2008 +0000
+++ b/Python/pystate.c	Mon Jan 21 07:11:11 2008 +0000
@@ -240,6 +240,7 @@
 {
 	PyInterpreterState *interp;
 	PyThreadState **p;
+	PyThreadState *prev_p = NULL;
 	if (tstate == NULL)
 		Py_FatalError("PyThreadState_Delete: NULL tstate");
 	interp = tstate->interp;
@@ -252,6 +253,15 @@
 				"PyThreadState_Delete: invalid tstate");
 		if (*p == tstate)
 			break;
+		if (*p == prev_p)
+			Py_FatalError(
+				"PyThreadState_Delete: small circular list(!)"
+                                " and tstate not found.");
+		prev_p = *p;
+		if ((*p)->next == interp->tstate_head)
+			Py_FatalError(
+				"PyThreadState_Delete: circular list(!) and"
+                                " tstate not found.");
 	}
 	*p = tstate->next;
 	HEAD_UNLOCK();