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util: avoid glib event loop workaround where possible

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I previously did a workaround for a glib event loop race
that causes crashes:

  commit 0db4743645b7a0611a3c0687f834205c9956f7fc
  Author: Daniel P. Berrangé <berrange@redhat.com>
  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.

Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Tested-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
This commit is contained in:
Daniel P. Berrangé 2020-11-25 17:59:16 +00:00
parent 829142699e
commit 6d69afe451
1 changed files with 21 additions and 8 deletions
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29
src/util/vireventglib.c
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@ -189,9 +189,21 @@ virEventGLibHandleFind(int watch)
* If the last reference to a GSource is released in a non-main * If the last reference to a GSource is released in a non-main
* thread we're exposed to a race condition that causes a * thread we're exposed to a race condition that causes a
* crash: * 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)
static gboolean static gboolean
virEventGLibSourceUnrefIdle(gpointer data) virEventGLibSourceUnrefIdle(gpointer data)
{ {
@ -201,6 +213,7 @@ virEventGLibSourceUnrefIdle(gpointer data)
return FALSE; return FALSE;
} }
#endif
static void static void
@ -231,7 +244,7 @@ virEventGLibHandleUpdate(int watch,
if (data->source != NULL) { if (data->source != NULL) {
VIR_DEBUG("Removed old handle source=%p", data->source); VIR_DEBUG("Removed old handle source=%p", data->source);
g_source_destroy(data->source); g_source_destroy(data->source);
g_idle_add(virEventGLibSourceUnrefIdle, data->source); g_vir_source_unref_safe(data->source);
} }
data->source = virEventGLibAddSocketWatch( data->source = virEventGLibAddSocketWatch(
@ -245,7 +258,7 @@ virEventGLibHandleUpdate(int watch,
VIR_DEBUG("Removed old handle source=%p", data->source); VIR_DEBUG("Removed old handle source=%p", data->source);
g_source_destroy(data->source); g_source_destroy(data->source);
g_idle_add(virEventGLibSourceUnrefIdle, data->source); g_vir_source_unref_safe(data->source);
data->source = NULL; data->source = NULL;
data->events = 0; data->events = 0;
} }
@ -294,7 +307,7 @@ virEventGLibHandleRemove(int watch)
if (data->source != NULL) { if (data->source != NULL) {
g_source_destroy(data->source); g_source_destroy(data->source);
g_idle_add(virEventGLibSourceUnrefIdle, data->source); g_vir_source_unref_safe(data->source);
data->source = NULL; data->source = NULL;
data->events = 0; data->events = 0;
} }
@ -427,7 +440,7 @@ virEventGLibTimeoutUpdate(int timer,
if (interval >= 0) { if (interval >= 0) {
if (data->source != NULL) { if (data->source != NULL) {
g_source_destroy(data->source); g_source_destroy(data->source);
g_idle_add(virEventGLibSourceUnrefIdle, data->source); g_vir_source_unref_safe(data->source);
} }
data->interval = interval; data->interval = interval;
@ -437,7 +450,7 @@ virEventGLibTimeoutUpdate(int timer,
goto cleanup; goto cleanup;
g_source_destroy(data->source); g_source_destroy(data->source);
g_idle_add(virEventGLibSourceUnrefIdle, data->source); g_vir_source_unref_safe(data->source);
data->source = NULL; data->source = NULL;
} }
@ -486,7 +499,7 @@ virEventGLibTimeoutRemove(int timer)
if (data->source != NULL) { if (data->source != NULL) {
g_source_destroy(data->source); g_source_destroy(data->source);
g_idle_add(virEventGLibSourceUnrefIdle, data->source); g_vir_source_unref_safe(data->source);
data->source = NULL; data->source = NULL;
} }