Make psutil optional

synapse/metrics/__init__.py

@@ -68,9 +68,18 @@ def register_cache(self, *args, **kwargs):
 
 
 def register_memory_metrics(hs):
-    metric = MemoryUsageMetric(hs)
+    try:
+        import psutil
+        process = psutil.Process()
+        process.memory_info().rss
+    except (ImportError, AttributeError):
+        logger.warn(
+            "psutil is not installed or incorrect version."
+            " Disabling memory metrics."
+        )
+        return
+    metric = MemoryUsageMetric(hs, psutil)
     all_metrics.append(metric)
-    return metric
 
 
 def get_metrics_for(pkg_name):

synapse/metrics/metric.py

@@ -16,8 +16,6 @@
 
 from itertools import chain
 
-import psutil
-
 
 # TODO(paul): I can't believe Python doesn't have one of these
 def map_concat(func, items):
@@ -167,9 +165,10 @@ class MemoryUsageMetric(object):
     UPDATE_HZ = 2  # number of times to get memory per second
     WINDOW_SIZE_SEC = 30  # the size of the window in seconds
 
-    def __init__(self, hs):
+    def __init__(self, hs, psutil):
         clock = hs.get_clock()
         self.memory_snapshots = []
+
         self.process = psutil.Process()
 
         clock.looping_call(self._update_curr_values, 1000 / self.UPDATE_HZ)

synapse/python_dependencies.py

@@ -36,7 +36,6 @@
     "blist": ["blist"],
     "pysaml2>=3.0.0,<4.0.0": ["saml2>=3.0.0,<4.0.0"],
     "pymacaroons-pynacl": ["pymacaroons"],
-    "psutil>=2.0.0": ["psutil>=2.0.0"],
 }
 CONDITIONAL_REQUIREMENTS = {
     "web_client": {
@@ -52,6 +51,9 @@
     "ldap": {
         "ldap3>=1.0": ["ldap3>=1.0"],
     },
+    "psutil": {
+        "psutil>=2.0.0": ["psutil>=2.0.0"],
+    },
 }