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| author | Anders Svensson <[email protected]> | 2015-07-18 14:04:28 +0200 |
|---|---|---|
| committer | Anders Svensson <[email protected]> | 2015-07-19 11:08:21 +0200 |
| commit | 4f365c072b6df771004b388dd7e66f08e37ac5e7 (patch) | |
| tree | c3fe3f7437c0a91c1ee4126aaf4608507ee39835 | |
| parent | 862af31d8a91b56711e3da554bb08247b7ee43cd (diff) | |
| download | otp-4f365c072b6df771004b388dd7e66f08e37ac5e7.tar.gz otp-4f365c072b6df771004b388dd7e66f08e37ac5e7.tar.bz2 otp-4f365c072b6df771004b388dd7e66f08e37ac5e7.zip | |
Don't start watchdog timers unnecessarily
In particular, restart the timer with each incoming Diameter message,
only when the previous timer has expired. Doing so has been seen to
result in high lock contention at load, as in the example below:
(diameter@test)9> lcnt:conflicts([{print, [name, tries, ratio, time]}]).
lock #tries collisions [%] time [us]
----- ------- --------------- ----------
bif_timers 7844528 99.4729 1394434884
db_tab 17240988 1.7947 6286664
timeofday 7358692 5.6729 1399624
proc_link 4814938 2.2736 482985
drv_ev_state 2324012 0.5951 98920
run_queue 21768213 0.2091 63516
pollset 1190174 1.7170 42499
pix_lock 1956 2.5562 39770
make_ref 4697067 0.3669 20211
proc_msgq 9475944 0.0295 5200
timer_wheel 5325966 0.0568 2654
proc_main 10005332 2.8190 1079
pollset_rm_list 59768 1.7752 480
| -rw-r--r-- | lib/diameter/src/base/diameter_watchdog.erl | 41 |
1 files changed, 27 insertions, 14 deletions
diff --git a/lib/diameter/src/base/diameter_watchdog.erl b/lib/diameter/src/base/diameter_watchdog.erl index 9844f58ab2..0607c72818 100644 --- a/lib/diameter/src/base/diameter_watchdog.erl +++ b/lib/diameter/src/base/diameter_watchdog.erl @@ -65,7 +65,10 @@ %% end PCB parent = self() :: pid(), %% service process transport :: pid() | undefined, %% peer_fsm process - tref :: reference(), %% reference for current watchdog timer + tref :: reference() %% reference for current watchdog timer + | integer() %% monotonic time + | tuple() %% now() + | undefined, dictionary :: module(), %% common dictionary receive_data :: term(), %% term passed into diameter_service with incoming message @@ -446,11 +449,12 @@ transition({recv, TPid, Name, Pkt}, #watchdog{transport = TPid} = S) -> %% Current watchdog has timed out. transition({timeout, TRef, tw}, #watchdog{tref = TRef} = S) -> - set_watchdog(timeout(S)); + set_watchdog(0, timeout(S)); -%% Timer was canceled after message was already sent. -transition({timeout, _, tw}, #watchdog{}) -> - ok; +%% Message has arrived since the timer was started: subtract time +%% already elapsed from new timer. +transition({timeout, _, tw}, #watchdog{tref = T0} = S) -> + set_watchdog(diameter_lib:micro_diff(T0) div 1000, S); %% State query. transition({state, Pid}, #watchdog{status = S}) -> @@ -526,18 +530,27 @@ role() -> %% set_watchdog/1 -set_watchdog(#watchdog{tw = TwInit, - tref = TRef} - = S) -> - cancel(TRef), - S#watchdog{tref = erlang:start_timer(tw(TwInit), self(), tw)}; +%% Timer not yet set. +set_watchdog(#watchdog{tref = undefined} = S) -> + set_watchdog(0, S); + +%% Timer already set: start at new one only at expiry. +set_watchdog(#watchdog{} = S) -> + S#watchdog{tref = diameter_lib:now()}; + set_watchdog(stop = No) -> No. -cancel(undefined) -> - ok; -cancel(TRef) -> - erlang:cancel_timer(TRef). +%% set_watchdog/2 + +set_watchdog(Ms, #watchdog{tw = TwInit} = S) -> + S#watchdog{tref = erlang:start_timer(tw(TwInit, Ms), self(), tw)}. + +%% A callback could return anything, so ensure the result isn't +%% negative. Don't prevent abuse, even though the smallest valid +%% timeout is 4000. +tw(TwInit, Ms) -> + max(tw(TwInit) - Ms, 0). tw(T) when is_integer(T), T >= 6000 -> |