[PATCH 2/2] Add a runtime parameter for expiry_log_threshold.

[Martin Blix Grydeland]

On busy servers, the logging and especially the object counters will
not reflect the work done by the expiry timer is very busy and does
not sleep (and flush the counters and log). This patch adds a
configurable maximum number of objects expired before updating the
counters and flushing the logs.
---
 bin/varnishd/cache/cache_expire.c |    7 ++++++-
 bin/varnishd/common/params.h      |    1 +
 bin/varnishd/mgt/mgt_param.c      |    6 ++++++
 3 files changed, 13 insertions(+), 1 deletions(-)

diff --git a/bin/varnishd/cache/cache_expire.c b/bin/varnishd/cache/cache_expire.c
index edbd52c..dbf21aa 100644
--- a/bin/varnishd/cache/cache_expire.c
+++ b/bin/varnishd/cache/cache_expire.c
@@ -336,15 +336,19 @@ exp_timer(struct worker *wrk, void *priv)
 	double t;
 	struct object *o;
 	struct vsl_log vsl;
+	unsigned i = 0;
 
 	(void)priv;
 	VSL_Setup(&vsl, NULL, 0);
 	t = VTIM_real();
 	oc = NULL;
 	while (1) {
-		if (oc == NULL) {
+		if (oc == NULL || i >= cache_param->expiry_log_threshold) {
 			VSL_Flush(&vsl, 0);
 			WRK_SumStat(wrk);
+			i = 0;
+		}
+		if (oc == NULL) {
 			VTIM_sleep(cache_param->expiry_sleep);
 			t = VTIM_real();
 		}
@@ -404,6 +408,7 @@ exp_timer(struct worker *wrk, void *priv)
 		Lck_Unlock(&lru->mtx);
 
 		VSC_C_main->n_expired++;
+		i++;
 
 		CHECK_OBJ_NOTNULL(oc->objhead, OBJHEAD_MAGIC);
 		o = oc_getobj(&wrk->stats, oc);
diff --git a/bin/varnishd/common/params.h b/bin/varnishd/common/params.h
index 6e502fd..b30a8b4 100644
--- a/bin/varnishd/common/params.h
+++ b/bin/varnishd/common/params.h
@@ -163,6 +163,7 @@ struct params {
 
 	/* Expiry pacer parameters */
 	double			expiry_sleep;
+	unsigned		expiry_log_threshold;
 
 	/* Acceptor pacer parameters */
 	double			acceptor_sleep_max;
diff --git a/bin/varnishd/mgt/mgt_param.c b/bin/varnishd/mgt/mgt_param.c
index f6493ad..ae6d6d0 100644
--- a/bin/varnishd/mgt/mgt_param.c
+++ b/bin/varnishd/mgt/mgt_param.c
@@ -820,6 +820,12 @@ static const struct parspec input_parspec[] = {
 		"for it to do.\n",
 		0,
 		"1", "seconds" },
+	{ "expiry_log_threshold", tweak_uint, &mgt_param.expiry_log_threshold,
+		1, UINT_MAX,
+		"Maximum number of objects expired without the expiry thread"
+		" sleeping before flushing the log.\n",
+		0,
+		"100", "objects" },
 	{ "pipe_timeout", tweak_timeout, &mgt_param.pipe_timeout, 0, 0,
 		"Idle timeout for PIPE sessions. "
 		"If nothing have been received in either direction for "
-- 
1.7.4.1