[PATCH v2] Fix fiber_join() hang in case fiber_cancel() was called
Serge Petrenko
sergepetrenko at tarantool.org
Tue Feb 5 18:01:11 MSK 2019
In case a fiber joining another fiber gets cancelled, it stays suspended
forever and never finishes joining. This happens because fiber_cancel()
wakes the fiber and removes it from all execution queues.
Fix this by handling possible cancellation in fiber_join().
Closes #3948
---
Changes in v2:
- rewrote the test completely.
- instead of continuing to join if the fiber
is cancelled make the fiber to be joined
non-joinable and exit. This solution was
discussed verbally.
- revert comment changes for fiber_yield().
It really isn't a cancellation point.
src/fiber.c | 25 ++++++++++++++++---------
src/lua/fiber.c | 11 ++++++++++-
test/app/fiber.result | 33 +++++++++++++++++++++++++++++++++
test/app/fiber.test.lua | 17 +++++++++++++++++
4 files changed, 76 insertions(+), 10 deletions(-)
diff --git a/src/fiber.c b/src/fiber.c
index 6f3d0ab78..7e9a3d38d 100644
--- a/src/fiber.c
+++ b/src/fiber.c
@@ -396,18 +396,25 @@ fiber_join(struct fiber *fiber)
do {
fiber_yield();
+ if (fiber_is_cancelled())
+ break;
} while (! fiber_is_dead(fiber));
}
-
- /* Move exception to the caller */
- int ret = fiber->f_ret;
- if (ret != 0) {
- assert(!diag_is_empty(&fiber->diag));
- diag_move(&fiber->diag, &fiber()->diag);
+ if (! fiber_is_dead(fiber)) {
+ fiber_set_joinable(fiber, false);
+ diag_set(FiberIsCancelled);
+ return -1;
+ } else {
+ /* Move exception to the caller */
+ int ret = fiber->f_ret;
+ if (ret != 0) {
+ assert(!diag_is_empty(&fiber->diag));
+ diag_move(&fiber->diag, &fiber()->diag);
+ }
+ /* The fiber is already dead. */
+ fiber_recycle(fiber);
+ return ret;
}
- /* The fiber is already dead. */
- fiber_recycle(fiber);
- return ret;
}
/**
diff --git a/src/lua/fiber.c b/src/lua/fiber.c
index 8b17d6475..c655c5258 100644
--- a/src/lua/fiber.c
+++ b/src/lua/fiber.c
@@ -33,6 +33,7 @@
#include <fiber.h>
#include "lua/utils.h"
#include "backtrace.h"
+#include "exception.h"
#include <lua.h>
#include <lauxlib.h>
@@ -676,10 +677,18 @@ lbox_fiber_join(struct lua_State *L)
{
struct fiber *fiber = lbox_checkfiber(L, 1);
struct lua_State *child_L = fiber->storage.lua.stack;
- fiber_join(fiber);
+ int f_ret = fiber_join(fiber);
struct error *e = NULL;
int num_ret = 0;
int coro_ref = 0;
+
+ if (f_ret != 0 && diag_last_error(&fiber()->diag)->type ==
+ &type_FiberIsCancelled) {
+ /* The fiber was cancelled before we joined. */
+ luaL_testcancel(L);
+ }
+ luaL_testcancel(L);
+
if (child_L != NULL) {
coro_ref = lua_tointeger(child_L, -1);
lua_pop(child_L, 1);
diff --git a/test/app/fiber.result b/test/app/fiber.result
index ab7c1941b..f73d32671 100644
--- a/test/app/fiber.result
+++ b/test/app/fiber.result
@@ -1411,6 +1411,39 @@ l = nil
l1 = nil
---
...
+-- gh-3948 fiber.join() blocks if fiber is cancelled.
+function another_func() fiber.yield() end
+---
+...
+test_run:cmd("setopt delimiter ';'")
+---
+- true
+...
+function func()
+ local fib = fiber.create(another_func)
+ fib:set_joinable(true)
+ fib:join()
+end;
+---
+...
+f = fiber.create(func)
+f:cancel()
+while f:status() ~= 'dead' do fiber.sleep(0.01) end;
+---
+...
+test_run:cmd("setopt delimiter ''");
+---
+- true
+...
+f = nil
+---
+...
+func = nil
+---
+...
+another_func = nil
+---
+...
-- cleanup
test_run:cmd("clear filter")
---
diff --git a/test/app/fiber.test.lua b/test/app/fiber.test.lua
index 2762047e4..98bb8f3e1 100644
--- a/test/app/fiber.test.lua
+++ b/test/app/fiber.test.lua
@@ -602,6 +602,23 @@ f = nil
l = nil
l1 = nil
+-- gh-3948 fiber.join() blocks if fiber is cancelled.
+function another_func() fiber.yield() end
+test_run:cmd("setopt delimiter ';'")
+function func()
+ local fib = fiber.create(another_func)
+ fib:set_joinable(true)
+ fib:join()
+end;
+f = fiber.create(func)
+f:cancel()
+while f:status() ~= 'dead' do fiber.sleep(0.01) end;
+
+test_run:cmd("setopt delimiter ''");
+f = nil
+func = nil
+another_func = nil
+
-- cleanup
test_run:cmd("clear filter")
--
2.17.2 (Apple Git-113)
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