Add exited status to SessionFlusher and rescue ThreadError (#1851)

* Add exited status to SessionFlusher and rescue ThreadError

* Specs

* Move rescue to add_session

* CHANGELOG

Author: sl0thentr0py

CHANGELOG.md

@@ -40,6 +40,8 @@
 - Respect `report_rescued_exceptions` config [#1847](https://github.com/getsentry/sentry-ruby/pull/1847)
   - Fixes [#1840](https://github.com/getsentry/sentry-ruby/issues/1840)
 - Rescue event's to JSON conversion error [#1853](https://github.com/getsentry/sentry-ruby/pull/1853)
+- Rescue `ThreadError` in `SessionFlusher` and stop creating threads if flusher is killed [#1851](https://github.com/getsentry/sentry-ruby/issues/1851)
+  - Fixes [#1848](https://github.com/getsentry/sentry-ruby/issues/1848)
 
 ### Refactoring
 

sentry-ruby/lib/sentry/session_flusher.rb

@@ -8,6 +8,7 @@ class SessionFlusher
 
     def initialize(configuration, client)
       @thread = nil
+      @exited = false
       @client = client
       @pending_aggregates = {}
       @release = configuration.release
@@ -29,9 +30,16 @@ def flush
     end
 
     def add_session(session)
+      return if @exited
       return unless @release
 
-      ensure_thread
+      begin
+        ensure_thread
+      rescue ThreadError
+        log_debug("Session flusher thread creation failed")
+        @exited = true
+        return
+      end
 
       return unless Session::AGGREGATE_STATUSES.include?(session.status)
       @pending_aggregates[session.aggregation_key] ||= init_aggregates(session.aggregation_key)
@@ -40,6 +48,8 @@ def add_session(session)
 
     def kill
       log_debug("Killing session flusher")
+
+      @exited = true
       @thread&.kill
     end
 

sentry-ruby/spec/sentry/session_flusher_spec.rb

@@ -126,12 +126,52 @@
       expect(pending_aggregates.keys.first).to be_a(Time)
       expect(pending_aggregates.values.first).to include({ errored: 0, exited: 1 })
     end
+
+    context "when thread creation fails" do
+      before do
+        expect(Thread).to receive(:new).and_raise(ThreadError)
+      end
+
+      it "doesn't create new thread" do
+        expect do
+          subject.add_session(session)
+        end.to change { Thread.list.count }.by(0)
+      end
+
+      it "noops" do
+        subject.add_session(session)
+        expect(subject.instance_variable_get(:@pending_aggregates)).to eq({})
+      end
+
+      it "logs error" do
+        subject.add_session(session)
+        expect(string_io.string).to match(/Session flusher thread creation failed/)
+      end
+    end
+
+    context "when killed" do
+      before do
+        subject.kill
+      end
+
+      it "noops" do
+        subject.add_session(session)
+        expect(subject.instance_variable_get(:@pending_aggregates)).to eq({})
+      end
+
+      it "doesn't create new thread" do
+        expect(Thread).not_to receive(:new)
+
+        expect do
+          subject.add_session(session)
+        end.to change { Thread.list.count }.by(0)
+      end
+    end
   end
 
   describe "#kill" do
     it "logs message when killing the thread" do
       subject.kill
-
       expect(string_io.string).to match(/Killing session flusher/)
     end
   end