Revert "Use SIGWINCH to print thread backtraces

Closes #2201

This reverts commit 3bf45fbf34.

History.md

@@ -8,7 +8,6 @@
   * `GC.compact` is called before fork if available (#2093)
   * Add `requests_count` to workers stats. (#2106)
   * Increases maximum URI path length from 2048 to 8196 bytes (#2167)
-  * Sending SIGWINCH to any Puma worker now prints currently active threads and their backtraces (#2195)
   * Force shutdown responses can be overridden by using the `lowlevel_error_handler` config (#2203)
 
 * Deprecations, Removals and Breaking API Changes
@@ -28,7 +27,7 @@
   * Ensure `BUNDLE_GEMFILE` is unspecified in workers if unspecified in master when using `prune_bundler` (#2154)
   * Rescue and log exceptions in hooks defined by users (on_worker_boot, after_worker_fork etc) (#1551)
   * Read directly from the socket in #read_and_drop to avoid raising further SSL errors (#2198)
-  
+
 * Refactor
   * Remove unused loader argument from Plugin initializer (#2095)
   * Simplify `Configuration.random_token` and remove insecure fallback (#2102)

docs/signals.md

@@ -40,7 +40,7 @@ Puma cluster responds to these signals:
 - `USR1` restart workers in phases, a rolling restart. This will not reload configuration file.
 - `HUP`  reopen log files defined in stdout_redirect configuration parameter. If there is no stdout_redirect option provided it will behave like `INT`
 - `INT` equivalent of sending Ctrl-C to cluster. Will attempt to finish then exit.
-- `WINCH` (`INFO` on BSD-based systems) prints a thread backtrace. This is useful for debugging infinite loops or slow performance.
+- `CHLD`
 
 ## Callbacks order in case of different signals
 

lib/puma/launcher.rb

@@ -452,18 +452,13 @@ module Puma
         log "*** SIGHUP not implemented, signal based logs reopening unavailable!"
       end
 
-      begin
-        Signal.trap "SIGWINCH" do
-          log_backtrace
-        end
-      rescue Exception
-        log "*** SIGWINCH not implemented, signal based thread backtraces unavailable!"
-      end
-
       begin
         unless Puma.jruby? # INFO in use by JVM already
           Signal.trap "SIGINFO" do
-            log_backtrace
+            thread_status do |name, backtrace|
+              @events.log name
+              @events.log backtrace.map { |bt| "  #{bt}" }
+            end
           end
         end
       rescue Exception
@@ -472,13 +467,6 @@ module Puma
       end
     end
 
-    def log_backtrace
-      thread_status do |name, backtrace|
-        @events.log name
-        @events.log backtrace.map { |bt| "  #{bt}" }
-      end
-    end
-
     def require_rubygems_min_version!(min_version, feature)
       return if min_version <= Gem::Version.new(Gem::VERSION)
 

test/test_integration_cluster.rb

@@ -33,16 +33,18 @@ class TestIntegrationCluster < TestIntegration
     end
   end
 
-  def test_sigwinch_thread_print
-    skip_unless_signal_exist? :WINCH
-
-    signal_thread_backtrace :WINCH
-  end
-
   def test_siginfo_thread_print
     skip_unless_signal_exist? :INFO
 
-    signal_thread_backtrace :INFO
+    cli_server "-w #{WORKERS} -q test/rackup/hello.ru"
+    worker_pids = get_worker_pids
+    output = []
+    t = Thread.new { output << @server.readlines }
+    Process.kill :INFO, worker_pids.first
+    Process.kill :INT , @pid
+    t.join
+
+    assert_match "Thread: TID", output.join
   end
 
   def test_usr2_restart
@@ -133,18 +135,6 @@ class TestIntegrationCluster < TestIntegration
 
   private
 
-  def signal_thread_backtrace(signal)
-    cli_server "-w #{WORKERS} -q test/rackup/hello.ru"
-    worker_pids = get_worker_pids
-    output = []
-    t = Thread.new { output << @server.readlines }
-    Process.kill signal, worker_pids.first
-    Process.kill :INT , @pid
-    t.join
-
-    assert_match "Thread: TID", output.join
-  end
-
   # Send requests 10 per second.  Send 10, then :TERM server, then send another 30.
   # No more than 10 should throw Errno::ECONNRESET.
   def term_closes_listeners(unix: false)