Middleware for Monitoring Memory

EDUCATOR-274

cms/envs/common.py

@@ -364,6 +364,9 @@ simplefilter('ignore')
 MIDDLEWARE_CLASSES = (
     'crum.CurrentRequestUserMiddleware',
     'request_cache.middleware.RequestCache',
+
+    'openedx.core.djangoapps.monitoring_utils.middleware.MonitoringMemoryMiddleware',
+
     'openedx.core.djangoapps.header_control.middleware.HeaderControlMiddleware',
     'django.middleware.cache.UpdateCacheMiddleware',
     'django.middleware.common.CommonMiddleware',

openedx/core/djangoapps/monitoring_utils/middleware.py

@@ -17,6 +17,7 @@ except ImportError:
     log.warning("Unable to load NewRelic agent module")
     newrelic = None  # pylint: disable=invalid-name
 
+import psutil
 import request_cache
 
 REQUEST_CACHE_KEY = 'monitoring_custom_metrics'
@@ -72,3 +73,83 @@ class MonitoringCustomMetrics(object):
         """
         self._batch_report()
         return None
+
+
+class MonitoringMemoryMiddleware(object):
+    """
+    Middleware for monitoring memory usage.
+    """
+    memory_data_key = u'memory_data'
+
+    def process_request(self, request):
+        log_prefix = self._log_prefix(u"Before", request)
+        self._cache[self.memory_data_key] = self._memory_data(log_prefix)
+
+    def process_response(self, request, response):
+        log_prefix = self._log_prefix(u"After", request)
+        new_memory_data = self._memory_data(log_prefix)
+
+        log_prefix = self._log_prefix(u"Diff", request)
+        self._diff_memory_data(log_prefix, new_memory_data, self._cache.get(self.memory_data_key))
+        return response
+
+    @property
+    def _cache(self):
+        """
+        Namespaced request cache for tracking memory usage.
+        """
+        return request_cache.get_cache(name='monitoring_memory')
+
+    def _log_prefix(self, prefix, request):
+        """
+        Returns a formatted prefix for logging for the given request.
+        """
+        return u"{} request '{} {}'".format(prefix, request.method, request.path)
+
+    def _memory_data(self, log_prefix):
+        """
+        Returns a dict with information for current memory utilization.
+        Uses log_prefix in log statements.
+        """
+        machine_data = psutil.virtual_memory()
+
+        process = psutil.Process()
+        process_data = {
+            'memory_info': process.get_memory_info(),
+            'ext_memory_info': process.get_ext_memory_info(),
+            'memory_percent': process.get_memory_percent(),
+            'cpu_percent': process.get_cpu_percent(),
+        }
+
+        log.info(u"%s Machine memory usage: %s; Process memory usage: %s", log_prefix, machine_data, process_data)
+        return {
+            'machine_data': machine_data,
+            'process_data': process_data,
+        }
+
+    def _log_diff_memory_data(self, prefix, new_memory_data, old_memory_data):
+        """
+        Computes and logs the difference in memory utilization
+        between the given old and new memory data.
+        """
+        def _vmem_used(memory_data):
+            return memory_data['machine_data'].used
+
+        def _process_mem_percent(memory_data):
+            return memory_data['process_data']['memory_percent']
+
+        def _process_rss(memory_data):
+            return memory_data['process_data']['memory_info'].rss
+
+        def _process_vms(memory_data):
+            return memory_data['process_data']['memory_info'].vms
+
+        if new_memory_data and old_memory_data:
+            log.info(
+                u"%s Diff Vmem used: %s, Diff percent memory: %s, Diff rss: %s, Diff vms: %s",
+                prefix,
+                _vmem_used(new_memory_data) - _vmem_used(old_memory_data),
+                _process_mem_percent(new_memory_data) - _process_mem_percent(old_memory_data),
+                _process_rss(new_memory_data) - _process_rss(old_memory_data),
+                _process_vms(new_memory_data) - _process_vms(old_memory_data),
+            )