From 0ab7340e571ea7472018a67e6a0d5dad614eccb4 Mon Sep 17 00:00:00 2001
From: drebs <drebs@leap.se>
Date: Sun, 9 Jul 2017 11:14:29 -0300
Subject: [benchmarks] separate memory sampling from cpu measurement

---
 testing/tests/benchmarks/conftest.py | 59 +++++++++++++++++++-----------------
 testing/tests/conftest.py            |  8 ++---
 testing/tox.ini                      |  4 +--
 3 files changed, 38 insertions(+), 33 deletions(-)

diff --git a/testing/tests/benchmarks/conftest.py b/testing/tests/benchmarks/conftest.py
index ac29f17f..3be17083 100644
--- a/testing/tests/benchmarks/conftest.py
+++ b/testing/tests/benchmarks/conftest.py
@@ -84,22 +84,26 @@ class ResourceWatcher(threading.Thread):
 
     sampling_interval = 0.1
 
-    def __init__(self):
+    def __init__(self, watch_memory):
         threading.Thread.__init__(self)
         self.process = psutil.Process(os.getpid())
         self.running = False
         # monitored resources
         self.cpu_percent = None
+        self.watch_memory = watch_memory
         self.memory_samples = []
         self.memory_percent = None
 
     def run(self):
         self.running = True
         self.process.cpu_percent()
+        # decide how long to sleep based on need to sample memory
+        sleep = self.sampling_interval if not self.watch_memory else 1
         while self.running:
-            sample = self.process.memory_percent(memtype='rss')
-            self.memory_samples.append(sample)
-            time.sleep(self.sampling_interval)
+            if self.watch_memory:
+                sample = self.process.memory_percent(memtype='rss')
+                self.memory_samples.append(sample)
+            time.sleep(sleep)
 
     def stop(self):
         self.running = False
@@ -107,47 +111,48 @@ class ResourceWatcher(threading.Thread):
         # save cpu usage info
         self.cpu_percent = self.process.cpu_percent()
         # save memory usage info
-        memory_percent = {
-            'sampling_interval': self.sampling_interval,
-            'samples': self.memory_samples,
-            'stats': {},
-        }
-        for stat in 'max', 'min', 'mean', 'std':
-            fun = getattr(numpy, stat)
-            memory_percent['stats'][stat] = fun(self.memory_samples)
-        self.memory_percent = memory_percent
-
-
-def _monitored_benchmark(benchmark_fixture, benchmark_function,
+        if self.watch_memory:
+            memory_percent = {
+                'sampling_interval': self.sampling_interval,
+                'samples': self.memory_samples,
+                'stats': {},
+            }
+            for stat in 'max', 'min', 'mean', 'std':
+                fun = getattr(numpy, stat)
+                memory_percent['stats'][stat] = fun(self.memory_samples)
+            self.memory_percent = memory_percent
+
+
+def _monitored_benchmark(benchmark_fixture, benchmark_function, request,
                          *args, **kwargs):
     # setup resource monitoring
-    watcher = ResourceWatcher()
+    watch_memory = _watch_memory(request)
+    watcher = ResourceWatcher(watch_memory)
     watcher.start()
     # run benchmarking function
     benchmark_function(*args, **kwargs)
     # store results
     watcher.stop()
     benchmark_fixture.extra_info.update({
-        'cpu_percent': watcher.cpu_percent,
-        'memory_percent': watcher.memory_percent,
+        'cpu_percent': watcher.cpu_percent
     })
+    if watch_memory:
+        benchmark_fixture.extra_info.update({
+            'memory_percent': watcher.memory_percent,
+        })
 
 
-def _watch_resources(request):
-    return request.config.getoption('--watch-resources')
+def _watch_memory(request):
+    return request.config.getoption('--watch-memory')
 
 
 @pytest.fixture
 def monitored_benchmark(benchmark, request):
-    if not _watch_resources(request):
-        return benchmark
     return functools.partial(
-        _monitored_benchmark, benchmark, benchmark)
+        _monitored_benchmark, benchmark, benchmark, request)
 
 
 @pytest.fixture
 def monitored_benchmark_with_setup(benchmark, request):
-    if not _watch_resources(request):
-        return benchmark.pedantic
     return functools.partial(
-        _monitored_benchmark, benchmark, benchmark.pedantic)
+        _monitored_benchmark, benchmark, benchmark.pedantic, request)
diff --git a/testing/tests/conftest.py b/testing/tests/conftest.py
index 994b1610..16ab699d 100644
--- a/testing/tests/conftest.py
+++ b/testing/tests/conftest.py
@@ -44,10 +44,10 @@ def pytest_addoption(parser):
     # the following option is only used in benchmarks, but has to be defined
     # here due to how pytest discovers plugins during startup.
     parser.addoption(
-        "--watch-resources", default=False, action="store_true",
-        help="whether to monitor CPU and memory percentages during test run. "
-             "**Warning**: enabling this will impact the time taken by the "
-             "benchmarked code, so use with caution!")
+        "--watch-memory", default=False, action="store_true",
+        help="whether to monitor memory percentages during test run. "
+             "**Warning**: enabling this will impact the time taken and the "
+             "CPU used by the benchmarked code, so use with caution!")
 
 
 @pytest.fixture
diff --git a/testing/tox.ini b/testing/tox.ini
index 88b27d48..5bfb8c50 100644
--- a/testing/tox.ini
+++ b/testing/tox.ini
@@ -76,9 +76,9 @@ commands =
 # we must make sure that installed pysqlcipher was built with the HAVE_USLEEP
 # flag, or we might have problems with concurrent db access.
     ./ensure-pysqlcipher-has-usleep.sh
-# run benchmarks twice: once for time and a second time for resources
+# run benchmarks twice: once for time and cpu and a second time for memory
     py.test --benchmark-only {posargs}
-    py.test --benchmark-only --watch-resources {posargs}
+    py.test --benchmark-only --watch-memory {posargs}
 passenv = HOST_HOSTNAME
 
 [testenv:code-check]
-- 
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