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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 resolves #616.
This commit is contained in:
Qi Wang 2017-01-30 15:54:16 -08:00 committed by Jason Evans
parent 7c124830a1
commit 7b53fe928e
1 changed files with 13 additions and 3 deletions
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16
src/stats.c
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@ -136,8 +136,16 @@ stats_arena_bins_print(void (*write_cb)(void *, const char *), void *cbopaque,
availregs = nregs * curruns; availregs = nregs * curruns;
milli = (availregs != 0) ? (1000 * curregs) / availregs milli = (availregs != 0) ? (1000 * curregs) / availregs
: 1000; : 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), malloc_snprintf(util, sizeof(util),
"0.00%zu", milli); "0.00%zu", milli);
} else if (milli < 100) { } else if (milli < 100) {
@ -146,8 +154,10 @@ stats_arena_bins_print(void (*write_cb)(void *, const char *), void *cbopaque,
} else if (milli < 1000) { } else if (milli < 1000) {
malloc_snprintf(util, sizeof(util), "0.%zu", malloc_snprintf(util, sizeof(util), "0.%zu",
milli); milli);
} else } else {
assert(milli == 1000);
malloc_snprintf(util, sizeof(util), "1"); malloc_snprintf(util, sizeof(util), "1");
}
if (config_tcache) { if (config_tcache) {
malloc_cprintf(write_cb, cbopaque, malloc_cprintf(write_cb, cbopaque,