Fix json perf counter print and add script to generate a chart

scripts/perf-plot.py

@@ -0,0 +1,43 @@
+#!/usr/bin/env python
+
+import matplotlib
+matplotlib.use('Agg')
+
+import matplotlib.pyplot as plt
+import json
+import sys
+
+stages_to_counters = {}
+stages_to_time = {}
+
+if len(sys.argv) != 2:
+    print("USAGE: {} <input file>".format(sys.argv[0]))
+    sys.exit(1)
+
+with open(sys.argv[1]) as fh:
+    for line in fh.readlines():
+        if "COUNTER" in line:
+            json_part = line[line.find("{"):]
+            x = json.loads(json_part)
+            counter = x['name']
+            if not (counter in stages_to_counters):
+                stages_to_counters[counter] = []
+                stages_to_time[counter] = []
+            stages_to_counters[counter].append(x['counts'])
+            stages_to_time[counter].append(x['now'])
+
+fig, ax = plt.subplots()
+
+for stage in stages_to_counters.keys():
+    plt.plot(stages_to_time[stage], stages_to_counters[stage], label=stage)
+
+plt.xlabel('ms')
+plt.ylabel('count')
+
+plt.legend(bbox_to_anchor=(0., 1.02, 1., .102), loc=3,
+           ncol=2, mode="expand", borderaxespad=0.)
+
+plt.locator_params(axis='x', nbins=10)
+plt.grid(True)
+
+plt.savefig("perf.pdf")

src/counter.rs

@@ -36,7 +36,7 @@ impl Counter {
         let times = self.times.fetch_add(1, Ordering::Relaxed);
         if times % self.lograte == 0 && times > 0 {
             info!(
-                "COUNTER:{{\"name:\":\"{}\", \"counts\": {}, \"nanos\": {}, \"samples\": {} \"rate\": {}, \"now\": {}}}",
+                "COUNTER:{{\"name\": \"{}\", \"counts\": {}, \"nanos\": {}, \"samples\": {}, \"rate\": {}, \"now\": {}}}",
                 self.name,
                 counts,
                 nanos,