--- a/toolkit/components/telemetry/ipc/TelemetryIPCAccumulator.cpp
+++ b/toolkit/components/telemetry/ipc/TelemetryIPCAccumulator.cpp
@@ -36,16 +36,17 @@ namespace TelemetryIPCAccumulator = mozi
 // sending them all at once. This value was chosen as a balance between data
 // timeliness and performance (see bug 1218576)
 const uint32_t kBatchTimeoutMs = 2000;
 
 // To stop growing unbounded in memory while waiting for kBatchTimeoutMs to
 // drain the probe accumulation arrays, we request an immediate flush if the
 // arrays manage to reach certain high water mark of elements.
 const size_t kHistogramAccumulationsArrayHighWaterMark = 5 * 1024;
+const size_t kScalarActionsArrayHighWaterMark = 10000;
 // With the current limits, events cost us about 1100 bytes each.
 // This limits memory use to about 10MB.
 const size_t kEventsArrayHighWaterMark = 10000;
 
 // This timer is used for batching and sending child process accumulations to the parent.
 nsITimer* gIPCTimer = nullptr;
 mozilla::Atomic<bool, mozilla::Relaxed> gIPCTimerArmed(false);
 mozilla::Atomic<bool, mozilla::Relaxed> gIPCTimerArming(false);
@@ -151,32 +152,42 @@ void
 TelemetryIPCAccumulator::RecordChildScalarAction(mozilla::Telemetry::ScalarID aId,
                                                  ScalarActionType aAction, const ScalarVariant& aValue)
 {
   StaticMutexAutoLock locker(gTelemetryIPCAccumulatorMutex);
   // Make sure to have the storage.
   if (!gChildScalarsActions) {
     gChildScalarsActions = new nsTArray<ScalarAction>();
   }
+  if (gChildScalarsActions->Length() == kScalarActionsArrayHighWaterMark) {
+    TelemetryIPCAccumulator::DispatchToMainThread(NS_NewRunnableFunction([]() -> void {
+      TelemetryIPCAccumulator::IPCTimerFired(nullptr, nullptr);
+    }));
+  }
   // Store the action.
   gChildScalarsActions->AppendElement(ScalarAction{aId, aAction, Some(aValue)});
   ArmIPCTimer(locker);
 }
 
 void
 TelemetryIPCAccumulator::RecordChildKeyedScalarAction(mozilla::Telemetry::ScalarID aId,
                                                       const nsAString& aKey,
                                                       ScalarActionType aAction,
                                                       const ScalarVariant& aValue)
 {
   StaticMutexAutoLock locker(gTelemetryIPCAccumulatorMutex);
   // Make sure to have the storage.
   if (!gChildKeyedScalarsActions) {
     gChildKeyedScalarsActions = new nsTArray<KeyedScalarAction>();
   }
+  if (gChildKeyedScalarsActions->Length() == kScalarActionsArrayHighWaterMark) {
+    TelemetryIPCAccumulator::DispatchToMainThread(NS_NewRunnableFunction([]() -> void {
+      TelemetryIPCAccumulator::IPCTimerFired(nullptr, nullptr);
+    }));
+  }
   // Store the action.
   gChildKeyedScalarsActions->AppendElement(
     KeyedScalarAction{aId, aAction, NS_ConvertUTF16toUTF8(aKey), Some(aValue)});
   ArmIPCTimer(locker);
 }
 
 void
 TelemetryIPCAccumulator::RecordChildEvent(const mozilla::TimeStamp& timestamp,