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Handle race in stats_arena_bins_print

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When multiple threads calling stats_print, race could happen as we read the
counters in separate mallctl calls; and the removed assertion could fail when
other operations happened in between the mallctl calls. For simplicity, output
"race" in the utilization field in this case.
This commit is contained in:
Qi Wang 2017-01-30 15:54:16 -08:00 committed by Qi Wang
parent 190f81c6d5
commit bbff6ca674
1 changed files with 11 additions and 2 deletions
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13
src/stats.c
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@ -133,8 +133,16 @@ stats_arena_bins_print(void (*write_cb)(void *, const char *), void *cbopaque,
availregs = nregs * curslabs;
milli = (availregs != 0) ? (1000 * curregs) / availregs
: 1000;
assert(milli <= 1000);
if (milli < 10) {
if (milli > 1000) {
/*
* Race detected: the counters were read in
* separate mallctl calls and concurrent
* operations happened in between. In this case
* no meaningful utilization can be computed.
*/
malloc_snprintf(util, sizeof(util), " race");
} else if (milli < 10) {
malloc_snprintf(util, sizeof(util),
"0.00%zu", milli);
} else if (milli < 100) {
@ -144,6 +152,7 @@ stats_arena_bins_print(void (*write_cb)(void *, const char *), void *cbopaque,
malloc_snprintf(util, sizeof(util), "0.%zu",
milli);
} else {
assert(milli == 1000);
malloc_snprintf(util, sizeof(util), "1");
}