2 files changed, 8 insertions, 0 deletions
diff --git a/changelog.d/8798.bugfix b/changelog.d/8798.bugfix
new file mode 100644
index 0000000000..9bdb2b51ea
--- /dev/null
+++ b/changelog.d/8798.bugfix
@@ -0,0 +1 @@
+Fix a bug where synctl could spawn duplicate copies of a worker. Contributed by Waylon Cude.
diff --git a/synctl b/synctl
index 9395ebd048..cfa9cec0c4 100755
--- a/synctl
+++ b/synctl
@@ -358,6 +358,13 @@ def main():
         for worker in workers:
             env = os.environ.copy()
 
+            # Skip starting a worker if its already running
+            if os.path.exists(worker.pidfile) and pid_running(
+                int(open(worker.pidfile).read())
+            ):
+                print(worker.app + " already running")
+                continue
+
             if worker.cache_factor:
                 os.environ["SYNAPSE_CACHE_FACTOR"] = str(worker.cache_factor)