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ClusterTopologyMonitorImpl::run: Add exponential backoff with jitter #1620

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ClusterTopologyMonitorImpl::run: Add exponential backoff with jitter #1620

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14 changes: 13 additions & 1 deletion ...ain/java/software/amazon/jdbc/hostlistprovider/monitoring/ClusterTopologyMonitorImpl.java
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Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,7 @@
import java.util.HashMap;
import java.util.List;
import java.util.Properties;
import java.util.Random;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorService;
Expand Down Expand Up @@ -872,12 +873,16 @@ protected String getHostEndpoint(final String nodeName) {
private static class NodeMonitoringWorker implements Runnable {

private static final Logger LOGGER = Logger.getLogger(NodeMonitoringWorker.class.getName());
private static final long INITIAL_BACKOFF_MS = 100;
private static final long MAX_BACKOFF_MS = 5000;
private static final Random random = new Random();

protected final FullServicesContainer servicesContainer;
protected final ClusterTopologyMonitorImpl monitor;
protected final HostSpec hostSpec;
protected final @Nullable HostSpec writerHostSpec;
protected boolean writerChanged = false;
protected int connectionAttempts = 0;

public NodeMonitoringWorker(
final FullServicesContainer servicesContainer,
Expand Down Expand Up @@ -905,9 +910,10 @@ public void run() {
try {
connection = this.servicesContainer.getPluginService().forceConnect(
hostSpec, this.monitor.monitoringProperties);
this.connectionAttempts = 0;
} catch (SQLException ex) {
// A problem occurred while connecting. We will try again on the next iteration.
TimeUnit.MILLISECONDS.sleep(100);
TimeUnit.MILLISECONDS.sleep(calculateBackoffWithJitter(this.connectionAttempts++));
continue;
}
}
Expand Down Expand Up @@ -1037,5 +1043,11 @@ private void readerThreadFetchTopology(final Connection connection, final @Nulla
LOGGER.fine(Utils.logTopology(hosts));
}
}

private static long calculateBackoffWithJitter(int attempt) {
long backoff = INITIAL_BACKOFF_MS * Math.round(Math.pow(2, Math.min(attempt, 6)));
backoff = Math.min(backoff, MAX_BACKOFF_MS);
return Math.round(backoff * (0.5 + random.nextDouble() * 0.5));
}
}
}