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85 lines
3.3 KiB
85 lines
3.3 KiB
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 e5226a8a6f..63693b93a6 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 d6ead7d672..d62135d878 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 0eebc0b891..d936457776 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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