From 33333335763f3109950ef0d9f009b8308f59bd7c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sandro=20J=C3=A4ckel?= <sandro.jaeckel@gmail.com>
Date: Mon, 3 Jul 2023 00:19:30 +0200
Subject: [PATCH] matrix-synapse: limit parallelism to 4 cores to be improve
 stability, formatting

On high core machines those easily can fail similar to:

matrix-synapse> tests.storage.test_room_search.MessageSearchTest.test_postgres_web_search_for_phrase
matrix-synapse> ===============================================================================
matrix-synapse> [ERROR]
matrix-synapse> Traceback (most recent call last):
matrix-synapse>   File "/build/source/tests/unittest.py", line 122, in new
matrix-synapse>     return code(orig, *args, **kwargs)
matrix-synapse>   File "/build/source/tests/unittest.py", line 216, in setUp
matrix-synapse>     return orig()
matrix-synapse>   File "/build/source/tests/unittest.py", line 338, in setUp
matrix-synapse>     self.hs = self.make_homeserver(self.reactor, self.clock)
matrix-synapse>   File "/build/source/tests/app/test_openid_listener.py", line 34, in make_homeserver
matrix-synapse>     hs = self.setup_test_homeserver(
matrix-synapse>   File "/build/source/tests/unittest.py", line 606, in setup_test_homeserver
matrix-synapse>     hs = setup_test_homeserver(self.addCleanup, **kwargs)
matrix-synapse>   File "/build/source/tests/server.py", line 921, in setup_test_homeserver
matrix-synapse>     prepare_database(
matrix-synapse>   File "/nix/store/2cc0p5apn2yg2fr5ii9mvb7fcwd74y26-matrix-synapse-1.86.0/lib/python3.10/site-packages/synapse/storage/prepare_database.py", line 155, in prepare_database
matrix-synapse>     raise UpgradeDatabaseException(EMPTY_DATABASE_ON_WORKER_ERROR)
matrix-synapse> synapse.storage.prepare_database.UpgradeDatabaseException: Uninitialised database: run the main synapse process to prepare the database schema before starting worker processes.
matrix-synapse>
---
 pkgs/servers/matrix-synapse/default.nix | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/pkgs/servers/matrix-synapse/default.nix b/pkgs/servers/matrix-synapse/default.nix
index 78458382c7e4..e278fc3aab00 100644
--- a/pkgs/servers/matrix-synapse/default.nix
+++ b/pkgs/servers/matrix-synapse/default.nix
@@ -86,21 +86,29 @@ buildPythonApplication rec {
 
   doCheck = !stdenv.isDarwin;
 
-  checkPhase = let testFlags = lib.optionalString (!stdenv.isAarch64) "-j $NIX_BUILD_CORES"; in ''
+  checkPhase = ''
     runHook preCheck
 
     # remove src module, so tests use the installed module instead
     rm -rf ./synapse
 
-    PYTHONPATH=".:$PYTHONPATH" ${python3.interpreter} -m twisted.trial ${testFlags} tests
+    # high parallelisem makes test suite unstable
+    # upstream uses 2 cores but 4 seems to be also stable
+    # https://github.com/matrix-org/synapse/blob/develop/.github/workflows/latest_deps.yml#L103
+    if (( $NIX_BUILD_CORES > 4)); then
+      NIX_BUILD_CORES=4
+    fi
+
+    PYTHONPATH=".:$PYTHONPATH" ${python3.interpreter} -m twisted.trial -j $NIX_BUILD_CORES tests
 
     runHook postCheck
   '';
 
-  passthru.tests = { inherit (nixosTests) matrix-synapse; };
-  passthru.plugins = plugins;
-  passthru.tools = tools;
-  passthru.python = python3;
+  passthru = {
+    tests = { inherit (nixosTests) matrix-synapse; };
+    inherit plugins tools;
+    python = python3;
+  };
 
   meta = with lib; {
     homepage = "https://matrix.org";