in_kafka: increase the poll-timeout if we run in own own thread

having 1ms timeout might make sense if the input plugin is
running in the main thread (not introducing delay for others).
but if we run in our very own thread then we should not over-
ride the fetch.wait.max.ms configuration value from the
kafka-consumer.

this in conjuntion with using autocommit again boosts the
throuhput significantly.

Signed-off-by: CoreidCC <[email protected]>

plugins/in_kafka/in_kafka.c

@@ -161,7 +161,7 @@ static int in_kafka_collect(struct flb_input_instance *ins,
     ret = FLB_EVENT_ENCODER_SUCCESS;
 
     while (ret == FLB_EVENT_ENCODER_SUCCESS) {
-        rkm = rd_kafka_consumer_poll(ctx->kafka.rk, 1);
+        rkm = rd_kafka_consumer_poll(ctx->kafka.rk, ctx->poll_timeount_ms);
 
         if (!rkm) {
             break;
@@ -246,6 +246,21 @@ static int in_kafka_init(struct flb_input_instance *ins,
         goto init_error;
     }
 
+    /* Set the kafka poll timeout dependend on wether we run in our own 
+     * or in the main event thread. 
+     * a) run in main event thread: 
+     *    -> minimize the delay we might create
+     * b) run in our own thread: 
+     *    -> optimize for throuput and relay on 'fetch.wait.max.ms' 
+     *       which is set to 500 by default default. lets set it to
+     *       twice that so that increasing fetch.wait.max.ms still
+     *       has an effect.
+     */
+    ctx->poll_timeount_ms = 1;   
+    if(ins->is_threaded) {
+        ctx->poll_timeount_ms = 1000;
+    }
+
     if (ctx->buffer_max_size > 0) {
         ctx->polling_threshold = ctx->buffer_max_size;
 

plugins/in_kafka/in_kafka.h

@@ -50,6 +50,7 @@ struct flb_in_kafka_config {
     size_t buffer_max_size;          /* Maximum size of chunk allocation */
     size_t polling_threshold;
     bool enable_auto_commit;
+    int poll_timeount_ms;
 };
 
 #endif