Support customization of termination signal for timeouts

We've been having a lot of timeouts on CI recently.  Our coredumps might
be helpful in tracking these down, but when we send `SIGTERM` or
`SIGKILL` we don't get coredumps.  This allows customization of which
signal is sent during these timeout messages, to allow for CI to set it
to `SIGSEGV` or similar, to force core dumps for debugging purposes.

stdlib/Distributed/src/managers.jl

@@ -736,7 +736,10 @@ function kill(manager::LocalManager, pid::Int, config::WorkerConfig; exit_timeou
         # Check to see if our child exited, and if not, send an actual kill signal
         if !process_exited(config.process)
             @warn("Failed to gracefully kill worker $(pid), sending SIGTERM")
-            kill(config.process, Base.SIGTERM)
+
+            # Support overriding this for the 
+            term_signal = parse(Int, get(ENV, "JULIA_TEST_TIMEOUT_SIGNUM", "$(Base.SIGTERM)"))
+            kill(config.process, term_signal)
 
             sleep(term_timeout)
             if !process_exited(config.process)

stdlib/LibGit2/test/libgit2.jl

@@ -62,7 +62,8 @@ function challenge_prompt(cmd::Cmd, challenges; timeout::Integer=60, debug::Bool
             end
 
             if process_running(p)
-                kill(p)
+                term_signal = parse(Int, get(ENV, "JULIA_TEST_TIMEOUT_SIGNUM", "$(Base.SIGTERM)"))
+                kill(p, term_signal)
                 put!(timer, :timeout)
             elseif success(p)
                 put!(timer, :success)

stdlib/Profile/test/runtests.jl

@@ -166,6 +166,7 @@ end
 end
 
 # Profile deadlocking in compilation (debuginfo registration)
+term_signal = parse(Int, get(ENV, "JULIA_TEST_TIMEOUT_SIGNUM", "$(Base.SIGTERM)"))
 let cmd = Base.julia_cmd()
     script = """
         using Profile
@@ -181,7 +182,7 @@ let cmd = Base.julia_cmd()
     t = Timer(120) do t
         # should be under 10 seconds, so give it 2 minutes then report failure
         println("KILLING BY PROFILE TEST WATCHDOG\n")
-        kill(p, Base.SIGTERM)
+        kill(p, term_signal)
         sleep(10)
         kill(p, Base.SIGKILL)
     end
@@ -209,7 +210,7 @@ if Sys.isbsd() || Sys.islinux()
             t = Timer(120) do t
                 # should be under 10 seconds, so give it 2 minutes then report failure
                 println("KILLING BY PROFILE TEST WATCHDOG\n")
-                kill(p, Base.SIGTERM)
+                kill(p, term_signal)
                 sleep(10)
                 kill(p, Base.SIGKILL)
                 close(iob)

stdlib/Sockets/test/runtests.jl

@@ -7,6 +7,7 @@ using Base: Experimental
 # so that we can attempt to get a "friendly" backtrace if something gets stuck
 # (although this'll also terminate any attempted debugging session)
 # expected test duration is about 5-10 seconds
+term_signal = parse(Int, get(ENV, "JULIA_TEST_TIMEOUT_SIGNUM", "$(Base.SIGTERM)"))
 function killjob(d)
     Core.print(Core.stderr, d)
     if Sys.islinux()
@@ -18,7 +19,7 @@ function killjob(d)
         ccall(:uv_kill, Cint, (Cint, Cint), getpid(), SIGINFO)
         sleep(5) # Allow time for profile to collect and print before killing
     end
-    ccall(:uv_kill, Cint, (Cint, Cint), getpid(), Base.SIGTERM)
+    ccall(:uv_kill, Cint, (Cint, Cint), getpid(), term_signal)
     nothing
 end
 sockets_watchdog_timer = Timer(t -> killjob("KILLING BY SOCKETS TEST WATCHDOG\n"), 600)

test/threads.jl

@@ -250,12 +250,13 @@ end
 
 # Spawn another process as a watchdog. If this test fails, it'll unrecoverably
 # hang in the event loop. Another process needs to kill it
+term_signal = parse(Int, get(ENV, "JULIA_TEST_TIMEOUT_SIGNUM", "$(Base.SIGTERM)"))
 cmd = """
     @async (Base.wait_readnb(stdin, 1); exit())
     sleep(100)
     isopen(stdin) || exit()
     println(stderr, "ERROR: Killing threads test due to watchdog expiry")
-    ccall(:uv_kill, Cint, (Cint, Cint), $(getpid()), Base.SIGTERM)
+    ccall(:uv_kill, Cint, (Cint, Cint), $(getpid()), $(term_signal))
 """
 proc = open(pipeline(`$(Base.julia_cmd()) -e $cmd`; stderr=stderr); write=true)