public void setTopNWorkerReportCycle(final int topNWorkerReportCycle) {
        if (topNWorkerReportCycle < 1) {
            return;
        }
        this.topNWorkerReportCycle = topNWorkerReportCycle;
    }
TopN is a special process, which hold a certain size of windows, and cache all top N records, save to the persistence
in low frequency.
oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/analysis/worker/TopNStreamProcessor.java