From ed41f7c398fa7a80642658e6b947904ece07059e Mon Sep 17 00:00:00 2001
From: Ian Butterworth <i.r.butterworth@gmail.com>
Date: Thu, 17 Feb 2022 12:52:29 -0500
Subject: [PATCH] Profile: Minor fixes. Signal handling fix. (#44199)

(cherry picked from commit 072c041f8fe19a3c94dc4a249de975c64a004d62)
---
 src/signal-handling.c           | 11 ++++++-----
 src/signals-unix.c              | 20 +++++++++++++++-----
 stdlib/Profile/Project.toml     |  3 ++-
 stdlib/Profile/src/Profile.jl   |  5 +++--
 stdlib/Profile/test/runtests.jl |  2 --
 5 files changed, 26 insertions(+), 15 deletions(-)

diff --git a/src/signal-handling.c b/src/signal-handling.c
index 142f03b6c899d..d9c53b0211eae 100644
--- a/src/signal-handling.c
+++ b/src/signal-handling.c
@@ -132,22 +132,23 @@ static size_t jl_safe_read_mem(const volatile char *ptr, char *out, size_t len)
 static double profile_autostop_time = -1.0;
 static double profile_peek_duration = 1.0; // seconds
 
-double jl_get_profile_peek_duration(void) {
+double jl_get_profile_peek_duration(void)
+{
     return profile_peek_duration;
 }
-void jl_set_profile_peek_duration(double t) {
+void jl_set_profile_peek_duration(double t)
+{
     profile_peek_duration = t;
-    return;
 }
 
 uintptr_t profile_show_peek_cond_loc;
 JL_DLLEXPORT void jl_set_peek_cond(uintptr_t cond)
 {
     profile_show_peek_cond_loc = cond;
-    return;
 }
 
-static void jl_check_profile_autostop(void) {
+static void jl_check_profile_autostop(void)
+{
     if ((profile_autostop_time != -1.0) && (jl_hrtime() > profile_autostop_time)) {
         profile_autostop_time = -1.0;
         jl_profile_stop_timer();
diff --git a/src/signals-unix.c b/src/signals-unix.c
index b2e3ef2952029..8a5822d451335 100644
--- a/src/signals-unix.c
+++ b/src/signals-unix.c
@@ -539,9 +539,13 @@ JL_DLLEXPORT int jl_profile_start_timer(void)
 
 JL_DLLEXPORT void jl_profile_stop_timer(void)
 {
-    if (running)
+    if (running) {
         timer_delete(timerprof);
-    running = 0;
+        // Because SIGUSR1 is multipurpose, care must be taken for running = 0 to be set after the timer has fully stopped.
+        // There may be a pending signal emitted from the timer so wait a few timer cycles
+        sleep_ms((nsecprof / GIGA) * 1000 * 3);
+        running = 0;
+    }
 }
 
 #elif defined(HAVE_ITIMER)
@@ -556,18 +560,24 @@ JL_DLLEXPORT int jl_profile_start_timer(void)
     timerprof.it_interval.tv_usec = 0;
     timerprof.it_value.tv_sec = nsecprof / GIGA;
     timerprof.it_value.tv_usec = ((nsecprof % GIGA) + 999) / 1000;
-    if (setitimer(ITIMER_PROF, &timerprof, NULL) == -1)
-        return -3;
+    // Because SIGUSR1 is multipurpose, set `running` before so that we know that the first SIGUSR1 came from the timer
     running = 1;
+    if (setitimer(ITIMER_PROF, &timerprof, NULL) == -1) {
+        running = 0;
+        return -3;
+    }
     return 0;
 }
 
 JL_DLLEXPORT void jl_profile_stop_timer(void)
 {
     if (running) {
-        running = 0;
         memset(&timerprof, 0, sizeof(timerprof));
         setitimer(ITIMER_PROF, &timerprof, NULL);
+        // Because SIGUSR1 is multipurpose, care must be taken for running = 0 to be set after the timer has fully stopped.
+        // There may be a pending signal emitted from the timer so wait a few timer cycles
+        sleep_ms((nsecprof / GIGA) * 1000 * 3);
+        running = 0;
     }
 }
 
diff --git a/stdlib/Profile/Project.toml b/stdlib/Profile/Project.toml
index 1d13dad22233a..334d475832b6d 100644
--- a/stdlib/Profile/Project.toml
+++ b/stdlib/Profile/Project.toml
@@ -5,9 +5,10 @@ uuid = "9abbd945-dff8-562f-b5e8-e1ebf5ef1b79"
 Printf = "de0858da-6303-5e67-8744-51eddeeeb8d7"
 
 [extras]
+Base64 = "2a0f44e3-6c83-55bd-87e4-b1978d98bd5f"
 Logging = "56ddb016-857b-54e1-b83d-db4d58db5568"
 Serialization = "9e88b42a-f829-5b0c-bbe9-9e923198166b"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [targets]
-test = ["Logging", "Serialization", "Test"]
+test = ["Base64", "Logging", "Serialization", "Test"]
diff --git a/stdlib/Profile/src/Profile.jl b/stdlib/Profile/src/Profile.jl
index 50e03d2c79a5a..b11dfb488c373 100644
--- a/stdlib/Profile/src/Profile.jl
+++ b/stdlib/Profile/src/Profile.jl
@@ -54,7 +54,7 @@ function _peek_report()
     iob = IOBuffer()
     ioc = IOContext(IOContext(iob, stdout), :displaysize=>displaysize(stdout))
     print(ioc, groupby = [:thread, :task])
-    Base.print(stdout, String(resize!(iob.data, iob.size)))
+    Base.print(stdout, String(take!(iob)))
 end
 # This is a ref so that it can be overridden by other profile info consumers.
 const peek_report = Ref{Function}(_peek_report)
@@ -73,7 +73,8 @@ Set the duration in seconds of the profile "peek" that is triggered via `SIGINFO
 set_peek_duration(t::Float64) = ccall(:jl_set_profile_peek_duration, Cvoid, (Float64,), t)
 
 precompile_script = """
-Profile.@profile sleep(0.5)
+import Profile
+Profile.@profile while Profile.len_data() < 1000; rand(10,10) * rand(10,10); end
 Profile.peek_report[]()
 Profile.clear()
 """
diff --git a/stdlib/Profile/test/runtests.jl b/stdlib/Profile/test/runtests.jl
index 50917b9797c7d..ab87d497fe93e 100644
--- a/stdlib/Profile/test/runtests.jl
+++ b/stdlib/Profile/test/runtests.jl
@@ -226,8 +226,6 @@ if Sys.isbsd() || Sys.islinux()
             end
         end
     end
-else
-    @warn "Skipping \"SIGINFO/SIGUSR1 profile triggering\" test as it is not supported on this platform"
 end
 
 @testset "FlameGraphs" begin