Bug 1412729 (part 4) - Attempt to reduce the size of GCMajor markers r=sfink

--HG--
extra : rebase_source : b1076c58337d3153bfdb27783719ef304ca75590

js/src/gc/Statistics.cpp

@@ -593,19 +593,28 @@ Statistics::renderJsonMessage(uint64_t timestamp, bool includeSlices) const
 void
 Statistics::formatJsonDescription(uint64_t timestamp, JSONPrinter& json) const
 {
+    // If you change JSON properties here, please update:
+    // Telemetry ping code: toolkit/components/telemetry/GCTelemetry.jsm
+    // Telemetry documentation: toolkit/components/telemetry/docs/data/main-ping.rst
+    // Telemetry tests: toolkit/components/telemetry/tests/browser/browser_TelemetryGC.js
+    // Perf.html: https://github.com/devtools-html/perf.html
+
     json.property("timestamp", timestamp);
 
     TimeDuration total, longest;
     gcDuration(&total, &longest);
     json.property("max_pause", longest, JSONPrinter::MILLISECONDS);
     json.property("total_time", total, JSONPrinter::MILLISECONDS);
-
+    // We might be able to omit reason if perf.html was able to retrive it
+    // from the first slice.  But it doesn't do this yet.
     json.property("reason", ExplainReason(slices_[0].reason));
     json.property("zones_collected", zoneStats.collectedZoneCount);
     json.property("total_zones", zoneStats.zoneCount);
     json.property("total_compartments", zoneStats.compartmentCount);
-    json.property("minor_gcs", counts[STAT_MINOR_GC]);
-    json.property("store_buffer_overflows", counts[STAT_STOREBUFFER_OVERFLOW]);
+    json.property("minor_gcs", getCount(STAT_MINOR_GC));
+    uint32_t storebufferOverflows = getCount(STAT_STOREBUFFER_OVERFLOW);
+    if (storebufferOverflows)
+        json.property("store_buffer_overflows", storebufferOverflows);
     json.property("slices", slices_.length());
 
     const double mmu20 = computeMMU(TimeDuration::FromMilliseconds(20));
@@ -618,11 +627,15 @@ Statistics::formatJsonDescription(uint64_t timestamp, JSONPrinter& json) const
     json.property("scc_sweep_total", sccTotal, JSONPrinter::MILLISECONDS);
     json.property("scc_sweep_max_pause", sccLongest, JSONPrinter::MILLISECONDS);
 
-    json.property("nonincremental_reason", ExplainAbortReason(nonincrementalReason_));
-    json.property("allocated", uint64_t(preBytes)/1024/1024);
+    if (nonincrementalReason_ != AbortReason::None)
+        json.property("nonincremental_reason", ExplainAbortReason(nonincrementalReason_));
     json.property("allocated_bytes", preBytes);
-    json.property("added_chunks", getCount(STAT_NEW_CHUNK));
-    json.property("removed_chunks", getCount(STAT_DESTROY_CHUNK));
+    uint32_t addedChunks = getCount(STAT_NEW_CHUNK);
+    if (addedChunks)
+        json.property("added_chunks", addedChunks);
+    uint32_t removedChunks = getCount(STAT_DESTROY_CHUNK);
+    if (removedChunks)
+        json.property("removed_chunks", removedChunks);
     json.property("major_gc_number", startingMajorGCNumber);
     json.property("minor_gc_number", startingMinorGCNumber);
     json.property("slice_number", startingSliceNumber);

toolkit/components/telemetry/GCTelemetry.jsm

@@ -110,7 +110,7 @@ class GCData {
 // make sure to update the JSON schema at:
 // https://github.com/mozilla-services/mozilla-pipeline-schemas/blob/master/telemetry/main.schema.json
 // You should also adjust browser_TelemetryGC.js.
-const MAX_GC_KEYS = 30;
+const MAX_GC_KEYS = 24;
 const MAX_SLICES = 4;
 const MAX_SLICE_KEYS = 12;
 const MAX_PHASES = 65;

toolkit/components/telemetry/docs/data/main-ping.rst

@@ -481,6 +481,7 @@ Structure:
           "total_zones": 9,
           "total_compartments": 309,
           "minor_gcs": 44,
+          // Present if non-zero.
           "store_buffer_overflows": 19,
           "mmu_20ms": 0,
           "mmu_50ms": 0,
@@ -488,11 +489,14 @@ Structure:
           // "AbortRequested", "KeepAtomsSet", "IncrementalDisabled",
           // "ModeChange", "MallocBytesTrigger", "GCBytesTrigger",
           // "ZoneChange", "CompartmentRevived".
-          "nonincremental_reason": "None",
-          "allocated": 37, // In megabytes.
+          // Present for non-incremental GCs only.
+          "nonincremental_reason": "GCBytesTrigger",
           "allocated_bytes": 38853696 // in bytes
+
+          // Present if non-zero.
           "added_chunks": 54,
           "removed_chunks": 12,
+
           // Total number of slices (some of which may not appear
           // in the "slices" array).
           "slices": 15,

toolkit/components/telemetry/tests/browser/browser_TelemetryGC.js

@@ -41,7 +41,7 @@ function check(entries) {
 
       foundGCs++;
 
-      ok(Object.keys(gc).length <= 30, "number of keys in GC is not too large");
+      ok(Object.keys(gc).length <= 24, "number of keys in GC is not too large");
 
       // Sanity check the GC data.
       ok("status" in gc, "status field present");