Use jemalloc by default

Author: Half-Shot

docker/README.md

@@ -207,11 +207,5 @@ healthcheck:
 
 ## Using jemalloc
 
-Jemalloc is embedded in the image and can be used instead of the default allocator
-(cf main README for more infos).
-
-To do so you can add this to your `docker run` commands:
-
-```
--e LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libjemalloc.so.2
-```
+Jemalloc is embedded in the image and will be used instead of the default allocator.
+You can read about jemalloc by reading the Synapse [README](../README.md)

docker/start.py

@@ -3,9 +3,9 @@
 import codecs
 import glob
 import os
+import platform
 import subprocess
 import sys
-
 import jinja2
 
 
@@ -213,6 +213,14 @@ def main(args, environ):
     if "-m" not in args:
         args = ["-m", synapse_worker] + args
 
+
+    jemallocpath = f"/usr/lib/{platform.machine()}-linux-gnu/libjemalloc.so.2"
+
+    if os.path.isfile(jemallocpath):
+        environ['LD_PRELOAD'] = jemallocpath
+    else:
+        log(f"Could not find {jemallocpath}, will not use")
+
     # if there are no config files passed to synapse, try adding the default file
     if not any(p.startswith("--config-path") or p.startswith("-c") for p in args):
         config_dir = environ.get("SYNAPSE_CONFIG_DIR", "/data")
@@ -248,9 +256,9 @@ def main(args, environ):
     args = ["python"] + args
     if ownership is not None:
         args = ["gosu", ownership] + args
-        os.execv("/usr/sbin/gosu", args)
+        os.execve("/usr/sbin/gosu", args, environ)
     else:
-        os.execv("/usr/local/bin/python", args)
+        os.execve("/usr/local/bin/python", args, environ)
 
 
 if __name__ == "__main__":