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jrgemignani pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/age.git
The following commit(s) were added to refs/heads/master by this push:
new 23cbe57a fix: remove pthread_mutex that causes self-deadlock on VLE
queries (#2433)
23cbe57a is described below
commit 23cbe57a1eedee9167221a0359b09e538ff6fc87
Author: crdv7 <[email protected]>
AuthorDate: Wed Jun 10 01:44:15 2026 +0800
fix: remove pthread_mutex that causes self-deadlock on VLE queries (#2433)
The pthread_mutex in manage_GRAPH_global_contexts() causes permanent
self-deadlock when ereport(ERROR) triggers siglongjmp while the mutex
is held, skipping pthread_mutex_unlock(). Any subsequent VLE query on
the same backend connection hangs forever in pthread_mutex_lock() with
__owner == own PID.
The mutex was introduced in PR #1881 (fix for issue #1878) but is
unnecessary: it protects a process-local static variable in
PostgreSQL's single-threaded backend model where no concurrent access
exists. The actual fix for #1878 was the Assert-to-runtime-check
conversion and strndup defensive copy, which remain untouched.
---
src/backend/utils/adt/age_global_graph.c | 63 +++++++-------------------------
1 file changed, 13 insertions(+), 50 deletions(-)
diff --git a/src/backend/utils/adt/age_global_graph.c
b/src/backend/utils/adt/age_global_graph.c
index 1c4a4601..397e0511 100644
--- a/src/backend/utils/adt/age_global_graph.c
+++ b/src/backend/utils/adt/age_global_graph.c
@@ -45,7 +45,6 @@
#include "catalog/ag_label.h"
#include "utils/ag_cache.h"
-#include <pthread.h>
/* defines */
#define VERTEX_HTAB_NAME "Vertex to edge lists " /* added a space at end for */
@@ -152,18 +151,8 @@ typedef struct GRAPH_global_context
struct GRAPH_global_context *next; /* next graph */
} GRAPH_global_context;
-/* container for GRAPH_global_context and its mutex */
-typedef struct GRAPH_global_context_container
-{
- /* head of the list */
- GRAPH_global_context *contexts;
-
- /* mutex to protect the list */
- pthread_mutex_t mutex_lock;
-} GRAPH_global_context_container;
-
/* global variable to hold the per process GRAPH global contexts */
-static GRAPH_global_context_container global_graph_contexts_container = {0};
+static GRAPH_global_context *global_graph_contexts = NULL;
/*
* VertexEdgeArray helpers — flat-array adjacency container used by
@@ -1054,12 +1043,10 @@ GRAPH_global_context *manage_GRAPH_global_contexts(char
*graph_name,
* 5) One or more other contexts do exist but, one or more are invalid.
*/
- /* lock the global contexts list */
- pthread_mutex_lock(&global_graph_contexts_container.mutex_lock);
/* free the invalidated GRAPH global contexts first */
prev_ggctx = NULL;
- curr_ggctx = global_graph_contexts_container.contexts;
+ curr_ggctx = global_graph_contexts;
while (curr_ggctx != NULL)
{
GRAPH_global_context *next_ggctx = curr_ggctx->next;
@@ -1076,7 +1063,7 @@ GRAPH_global_context *manage_GRAPH_global_contexts(char
*graph_name,
*/
if (prev_ggctx == NULL)
{
- global_graph_contexts_container.contexts = next_ggctx;
+ global_graph_contexts = next_ggctx;
}
else
{
@@ -1089,8 +1076,6 @@ GRAPH_global_context *manage_GRAPH_global_contexts(char
*graph_name,
/* if it wasn't successfull, there was a missing vertex entry */
if (!success)
{
- /* unlock the mutex so we don't get a deadlock */
-
pthread_mutex_unlock(&global_graph_contexts_container.mutex_lock);
ereport(ERROR, (errcode(ERRCODE_DATA_EXCEPTION),
errmsg("missing vertex or edge entry during
free")));
@@ -1106,7 +1091,7 @@ GRAPH_global_context *manage_GRAPH_global_contexts(char
*graph_name,
}
/* find our graph's context. if it exists, we are done */
- curr_ggctx = global_graph_contexts_container.contexts;
+ curr_ggctx = global_graph_contexts;
while (curr_ggctx != NULL)
{
if (curr_ggctx->graph_oid == graph_oid)
@@ -1114,8 +1099,6 @@ GRAPH_global_context *manage_GRAPH_global_contexts(char
*graph_name,
/* switch our context back */
MemoryContextSwitchTo(oldctx);
- /* we are done unlock the global contexts list */
- pthread_mutex_unlock(&global_graph_contexts_container.mutex_lock);
return curr_ggctx;
}
@@ -1125,9 +1108,9 @@ GRAPH_global_context *manage_GRAPH_global_contexts(char
*graph_name,
/* otherwise, we need to create one and possibly attach it */
new_ggctx = palloc0(sizeof(GRAPH_global_context));
- if (global_graph_contexts_container.contexts != NULL)
+ if (global_graph_contexts != NULL)
{
- new_ggctx->next = global_graph_contexts_container.contexts;
+ new_ggctx->next = global_graph_contexts;
}
else
{
@@ -1135,7 +1118,7 @@ GRAPH_global_context *manage_GRAPH_global_contexts(char
*graph_name,
}
/* set the global context variable */
- global_graph_contexts_container.contexts = new_ggctx;
+ global_graph_contexts = new_ggctx;
/* set the graph name and oid */
new_ggctx->graph_name = pstrdup(graph_name);
@@ -1157,8 +1140,6 @@ GRAPH_global_context *manage_GRAPH_global_contexts(char
*graph_name,
load_GRAPH_global_hashtables(new_ggctx);
freeze_GRAPH_global_hashtables(new_ggctx);
- /* unlock the global contexts list */
- pthread_mutex_unlock(&global_graph_contexts_container.mutex_lock);
/* switch back to the previous memory context */
MemoryContextSwitchTo(oldctx);
@@ -1170,18 +1151,16 @@ GRAPH_global_context *manage_GRAPH_global_contexts(char
*graph_name,
* Helper function to delete all of the global graph contexts used by the
* process. When done the global global_graph_contexts will be NULL.
*
- * NOTE: Function uses a MUTEX global_graph_contexts_mutex
+ *
*/
static bool delete_GRAPH_global_contexts(void)
{
GRAPH_global_context *curr_ggctx = NULL;
bool retval = false;
- /* lock contexts list */
- pthread_mutex_lock(&global_graph_contexts_container.mutex_lock);
/* get the first context, if any */
- curr_ggctx = global_graph_contexts_container.contexts;
+ curr_ggctx = global_graph_contexts;
/* free all GRAPH global contexts */
while (curr_ggctx != NULL)
@@ -1195,8 +1174,6 @@ static bool delete_GRAPH_global_contexts(void)
/* if it wasn't successfull, there was a missing vertex entry */
if (!success)
{
- /* unlock the mutex so we don't get a deadlock */
- pthread_mutex_unlock(&global_graph_contexts_container.mutex_lock);
ereport(ERROR, (errcode(ERRCODE_DATA_EXCEPTION),
errmsg("missing vertex or edge entry during
free")));
@@ -1209,10 +1186,8 @@ static bool delete_GRAPH_global_contexts(void)
}
/* reset the head of the contexts to NULL */
- global_graph_contexts_container.contexts = NULL;
+ global_graph_contexts = NULL;
- /* unlock the global contexts list */
- pthread_mutex_unlock(&global_graph_contexts_container.mutex_lock);
return retval;
}
@@ -1235,11 +1210,9 @@ static bool delete_specific_GRAPH_global_contexts(char
*graph_name)
/* get the graph oid */
graph_oid = get_graph_oid(graph_name);
- /* lock the global contexts list */
- pthread_mutex_lock(&global_graph_contexts_container.mutex_lock);
/* get the first context, if any */
- curr_ggctx = global_graph_contexts_container.contexts;
+ curr_ggctx = global_graph_contexts;
/* find the specified GRAPH global context */
while (curr_ggctx != NULL)
@@ -1256,7 +1229,7 @@ static bool delete_specific_GRAPH_global_contexts(char
*graph_name)
*/
if (prev_ggctx == NULL)
{
- global_graph_contexts_container.contexts = next_ggctx;
+ global_graph_contexts = next_ggctx;
}
else
{
@@ -1266,8 +1239,6 @@ static bool delete_specific_GRAPH_global_contexts(char
*graph_name)
/* free the current graph context */
success = free_specific_GRAPH_global_context(curr_ggctx);
- /* unlock the global contexts list */
- pthread_mutex_unlock(&global_graph_contexts_container.mutex_lock);
/* if it wasn't successfull, there was a missing vertex entry */
if (!success)
@@ -1285,8 +1256,6 @@ static bool delete_specific_GRAPH_global_contexts(char
*graph_name)
curr_ggctx = next_ggctx;
}
- /* unlock the global contexts list */
- pthread_mutex_unlock(&global_graph_contexts_container.mutex_lock);
/* we didn't find it, return false */
return false;
@@ -1347,19 +1316,15 @@ GRAPH_global_context *find_GRAPH_global_context(Oid
graph_oid)
{
GRAPH_global_context *ggctx = NULL;
- /* lock the global contexts lists */
- pthread_mutex_lock(&global_graph_contexts_container.mutex_lock);
/* get the root */
- ggctx = global_graph_contexts_container.contexts;
+ ggctx = global_graph_contexts;
while(ggctx != NULL)
{
/* if we found it return it */
if (ggctx->graph_oid == graph_oid)
{
- /* unlock the global contexts lists */
- pthread_mutex_unlock(&global_graph_contexts_container.mutex_lock);
return ggctx;
}
@@ -1368,8 +1333,6 @@ GRAPH_global_context *find_GRAPH_global_context(Oid
graph_oid)
ggctx = ggctx->next;
}
- /* unlock the global contexts lists */
- pthread_mutex_unlock(&global_graph_contexts_container.mutex_lock);
/* we did not find it so return NULL */
return NULL;
