From 3f7b53589c804e5bd29115b918fbb9b2b8a31e76 Mon Sep 17 00:00:00 2001
From: Shrikant Sharat Kandula <shrikant@appsmith.com>
Date: Thu, 20 Jun 2024 19:36:15 +0530
Subject: [PATCH] fix: Supervisor buffer overflow errors (#34351)
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Should fix the flood of buffer overflow errors we see from Supervisor.

The one "change" this PR has, is that all the logs from the Docker
container will now be coming from `stderr`, not `stdout`. I don't expect
it to cause any problems, but it _is_ a change in behaviour nonetheless.

Why do that? Because of the way Supervisor event listening works. This
fix is based on the conversation at
https://github.com/Supervisor/supervisor/issues/1417. Essentially that
`stdout` should be reserved as a communication channel between
Supervisord and the event-listener, and for logging, we should use
`stderr`.

**/test sanity**



<!-- This is an auto-generated comment: Cypress test results  -->
> [!TIP]
> 🟢 🟢 🟢 All cypress tests have passed! 🎉 🎉 🎉
> Workflow run:
<https://github.com/appsmithorg/appsmith/actions/runs/9592028116>
> Commit: 34a29eabc8dc82fb6a43b143e400d725d197a655
> <a
href="https://internal.appsmith.com/app/cypress-dashboard/rundetails-65890b3c81d7400d08fa9ee5?branch=master&workflowId=9592028116&attempt=1"
target="_blank">Cypress dashboard</a>.
> Tags: `@tag.Sanity`

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<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

- **Refactor**
- Improved logging by switching to `print` statements with explicit
flushing for more reliable output handling.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->
---
 .../supervisor/appsmith_supervisor_stdout.py  | 25 ++++++-------------
 1 file changed, 8 insertions(+), 17 deletions(-)

diff --git a/deploy/docker/fs/usr/lib/python3/dist-packages/supervisor/appsmith_supervisor_stdout.py b/deploy/docker/fs/usr/lib/python3/dist-packages/supervisor/appsmith_supervisor_stdout.py
index 966c7f13d9..39ffd0f17c 100644
--- a/deploy/docker/fs/usr/lib/python3/dist-packages/supervisor/appsmith_supervisor_stdout.py
+++ b/deploy/docker/fs/usr/lib/python3/dist-packages/supervisor/appsmith_supervisor_stdout.py
@@ -8,33 +8,24 @@ Originally taken from https://github.com/coderanger/supervisor-stdout/blob/973ba
 import sys
 
 
-def write_stdout(s):
-    sys.stdout.write(s)
-    sys.stdout.flush()
-
-
-def write_stderr(s):
-    sys.stderr.write(s)
-    sys.stderr.flush()
-
-
 def main():
     while 1:
-        write_stdout("READY\n")  # transition from ACKNOWLEDGED to READY
+        print("READY", flush=True)  # transition from ACKNOWLEDGED to READY
         line = sys.stdin.readline()  # read header line from stdin
         headers = dict([x.split(":") for x in line.split()])
         data = sys.stdin.read(int(headers["len"]))  # read the event payload
-        write_stdout(
-            "RESULT %s\n%s" % (len(data.encode("utf-8")), data)
+        print(
+            f"RESULT {len(data.encode('utf-8'))}\n{data}",
+            end="",
+            flush=True,
         )  # transition from READY to ACKNOWLEDGED
 
 
 def event_handler(event, response):
-    line, data = response.rstrip().decode().split("\n", 1)
+    line, *lines = response.rstrip().decode().split("\n", 1)
     headers = dict(x.split(":", 1) for x in line.split())
-    lines = data.split("\n")
-    prefix = "%s %s | " % (headers["processname"], headers["channel"])
-    print("\n".join(prefix + l for l in lines))
+    prefix = f"{headers['processname']} {headers['channel']} | "
+    print(*(prefix + l for l in lines), sep="\n", file=sys.stderr, flush=True)
 
 
 if __name__ == "__main__":