docs: fix durable-example based on feedback.

Author: karel-rehor

examples/src/main/java/com/influxdb/v3/durable/DurableExample.java

@@ -125,10 +125,16 @@ public static void main(final String[] args) {
 
           // borrow then return a client
           InfluxDBClient client = clientPool.borrowClient();
-          logger.info(" [writeTaskPointsOK " + count + "] Writing " + points.size()
-            + " points with client " + client.hashCode());
-          client.writePoints(points);
-          clientPool.returnClient(client);
+          try {
+            logger.info(" [writeTaskPointsOK " + count + "] Writing " + points.size()
+              + " points with client " + client.hashCode());
+            client.writePoints(points);
+          } catch (Exception e) {
+            logger.severe(" [writeTaskPointsOK " + count + "] Unexpected Error writing points "
+              + e.getMessage());
+          } finally {
+            clientPool.returnClient(client);
+          }
 
           LockSupport.parkNanos(TimeUnit.SECONDS.toNanos(10));
           count++;

examples/src/main/java/com/influxdb/v3/durable/InfluxClientPool.java

@@ -81,6 +81,9 @@ public synchronized InfluxDBClient borrowClient() {
       client = InfluxDBClient.getInstance(clientConfig);
       runners.add(client);
       if (activeCount() >= maxSize) {
+        // N.B. this is just an example implementation.
+        // For simplicity this _example_ will allow the maxSize value to be exceeded with a severe warning.
+        // In a production environment maxSize should be managed appropriately.
         logger.severe("Max pool size " + maxSize + " exceeded: " + "actives "
           + activeCount() + " idles " + idleCount()
           + " (hint: Is there a process hogging zombie clients?)");
@@ -152,11 +155,11 @@ public synchronized void close() throws Exception {
     }
   }
 
-  public int activeCount() {
+  public synchronized int activeCount() {
     return runners.size();
   }
 
-  public int idleCount() {
+  public synchronized int idleCount() {
     return idlers.size();
   }
 }