On 11/25/20 7:04 PM, Daniel P. Berrangé wrote:
I previously did a workaround for a glib event loop race
that causes crashes:
commit 0db4743645b7a0611a3c0687f834205c9956f7fc
Author: Daniel P. Berrangé <berrange@xxxxxxxxxx>
Date: Tue Jul 28 16:52:47 2020 +0100
util: avoid crash due to race in glib event loop code
it turns out that the workaround has a significant performance
penalty on I/O intensive workloads. We thus need to avoid the
workaround if we know we have a new enough glib to avoid the
race condition.
Signed-off-by: Daniel P. Berrangé <berrange@xxxxxxxxxx>
---
src/util/vireventglib.c | 29 +++++++++++++++++++++--------
1 file changed, 21 insertions(+), 8 deletions(-)
diff --git a/src/util/vireventglib.c b/src/util/vireventglib.c
index 6842c6e806..8c5495bfab 100644
--- a/src/util/vireventglib.c
+++ b/src/util/vireventglib.c
@@ -189,9 +189,21 @@ virEventGLibHandleFind(int watch)
* If the last reference to a GSource is released in a non-main
* thread we're exposed to a race condition that causes a
* crash:
- * https://gitlab.gnome.org/GNOME/glib/-/merge_requests/1358
- * Thus we're using an idle func to release our ref
+ *
+ * https://gitlab.gnome.org/GNOME/glib/-/merge_requests/1358
+ *
+ * Thus we're using an idle func to release our ref...
+ *
+ * ...but this imposes a significant performance penalty on
+ * I/O intensive workloads which are sensitive to the iterations
+ * of the event loop, so avoid the workaround if we know we have
+ * new enough glib.
*/
+#if GLIB_CHECK_VERSION(2, 64, 0)
+# define g_vir_source_unref_safe(source) g_source_unref(source)
+#else
+# define g_vir_source_unref_safe(source) g_idle_add(virEventGLibSourceUnrefIdle, source);
s/;//
+
Would something like the following be totally disgusting or only a bit?
#if !GLIB_CHECK_VERSION(2, 64, 0)
# define g_source_unref(source) g_idle_add(virEventGLibSourceUnrefIdle,
source)
#endif
- g_idle_add(...);
+ g_source_unref(...);
This way we could just drop the redefine once we upgrade min glib version.
Michal
