Increase logging buffer size to 256kb (#25922)

Author: Bruno Volpato

runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/logging/DataflowWorkerLoggingHandler.java

@@ -75,6 +75,13 @@ public class DataflowWorkerLoggingHandler extends Handler {
     BEAM_LOG_LEVEL_TO_CLOUD_LOG_LEVEL.put(BeamFnApi.LogEntry.Severity.Enum.CRITICAL, "CRITICAL");
   }
 
+  /**
+   * Buffer size to use when writing logs. This matches <a
+   * href="https://cloud.google.com/logging/quotas#log-limits">Logging usage limits</a> to avoid
+   * spreading the same log entry across multiple disk flushes.
+   */
+  private static final int LOGGING_WRITER_BUFFER_SIZE = 262144; // 256kb
+
   /**
    * Formats the throwable as per {@link Throwable#printStackTrace()}.
    *
@@ -278,7 +285,8 @@ public OutputStream get() {
       try {
         String filename = filepath + "." + formatter.format(new Date()) + ".log";
         return new BufferedOutputStream(
-            new FileOutputStream(new File(filename), true /* append */));
+            new FileOutputStream(new File(filename), true /* append */),
+            LOGGING_WRITER_BUFFER_SIZE);
       } catch (IOException e) {
         throw new RuntimeException(e);
       }