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86 lines
3.2 KiB
86 lines
3.2 KiB
7 years ago
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From 2a0feeb4252cbf1207f45e978fe7eb02bb0182ec Mon Sep 17 00:00:00 2001
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From: Kyle Walker <walker.kyle.t@gmail.com>
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Date: Thu, 30 Jun 2016 15:12:18 -0400
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Subject: [PATCH] manager: Only invoke a single sigchld per unit within a
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cleanup cycle
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By default, each iteration of manager_dispatch_sigchld() results in a unit level
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sigchld event being invoked. For scope units, this results in a scope_sigchld_event()
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which can seemingly stall for workloads that have a large number of PIDs within the
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scope. The stall exhibits itself as a SIG_0 being initiated for each u->pids entry
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as a result of pid_is_unwaited().
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v2:
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This patch resolves this condition by only paying to cost of a sigchld in the underlying
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scope unit once per sigchld iteration. A new "sigchldgen" member resides within the
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Unit struct. The Manager is incremented via the sd event loop, accessed via
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sd_event_get_iteration, and the Unit member is set to the same value as the manager each
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time that a sigchld event is invoked. If the Manager iteration value and Unit member
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match, the sigchld event is not invoked for that iteration.
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Cherry-picked from: 36f20ae3b2975e44b6ef17e453ae06a289e9a122
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Resolves: #1342173
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---
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src/core/manager.c | 13 ++++++++++++-
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src/core/unit.c | 1 +
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src/core/unit.h | 3 +++
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3 files changed, 16 insertions(+), 1 deletion(-)
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diff --git a/src/core/manager.c b/src/core/manager.c
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index e5226a8a6..63693b93a 100644
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--- a/src/core/manager.c
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+++ b/src/core/manager.c
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@@ -1747,14 +1747,25 @@ static int manager_dispatch_notify_fd(sd_event_source *source, int fd, uint32_t
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}
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static void invoke_sigchld_event(Manager *m, Unit *u, siginfo_t *si) {
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+ uint64_t iteration;
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+
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assert(m);
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assert(u);
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assert(si);
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+ sd_event_get_iteration(m->event, &iteration);
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+
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log_unit_debug(u->id, "Child "PID_FMT" belongs to %s", si->si_pid, u->id);
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unit_unwatch_pid(u, si->si_pid);
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- UNIT_VTABLE(u)->sigchld_event(u, si->si_pid, si->si_code, si->si_status);
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+
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+ if (UNIT_VTABLE(u)->sigchld_event) {
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+ if (set_size(u->pids) <= 1 || iteration != u->sigchldgen) {
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+ UNIT_VTABLE(u)->sigchld_event(u, si->si_pid, si->si_code, si->si_status);
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+ u->sigchldgen = iteration;
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+ } else
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+ log_debug("%s already issued a sigchld this iteration %llu, skipping. Pids still being watched %d", u->id, iteration, set_size(u->pids));
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+ }
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}
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static int manager_dispatch_sigchld(Manager *m) {
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diff --git a/src/core/unit.c b/src/core/unit.c
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index d6ead7d67..d62135d87 100644
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--- a/src/core/unit.c
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+++ b/src/core/unit.c
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@@ -94,6 +94,7 @@ Unit *unit_new(Manager *m, size_t size) {
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u->unit_file_state = _UNIT_FILE_STATE_INVALID;
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u->unit_file_preset = -1;
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u->on_failure_job_mode = JOB_REPLACE;
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+ u->sigchldgen = 0;
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return u;
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}
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diff --git a/src/core/unit.h b/src/core/unit.h
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index 0eebc0b89..d93645777 100644
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--- a/src/core/unit.h
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+++ b/src/core/unit.h
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@@ -167,6 +167,9 @@ struct Unit {
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* process SIGCHLD for */
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Set *pids;
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+ /* Used in sigchld event invocation to avoid repeat events being invoked */
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+ uint64_t sigchldgen;
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+
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/* Used during GC sweeps */
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unsigned gc_marker;
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