public long getGcTimePercentage() {
      return gcTimePercentage.get();
    }
Returns the percentage (0..100) of time that the JVM spent in GC pauses within the
observation window of the associated GCTimeMonitor.

@return GcTimePercentage.
iotdb-core/node-commons/src/main/java/org/apache/iotdb/commons/service/metric/JvmGcMonitorMetrics.java