David Pilato e32c7f1d72 Explain how to use bulk processor in a test context
When using a bulk processor in test, you might write something like:

```java
BulkProcessor bulkProcessor = BulkProcessor.builder(client, new BulkProcessor.Listener() {
    @Override public void beforeBulk(long executionId, BulkRequest request) {}
    @Override public void afterBulk(long executionId, BulkRequest request, BulkResponse response) {}
    @Override public void afterBulk(long executionId, BulkRequest request, Throwable failure) {}
})
        .setBulkActions(10000)
        .setFlushInterval(TimeValue.timeValueSeconds(10))
        .build();

for (int i = 0; i < 10000; i++) {
    bulkProcessor.add(new IndexRequest("foo", "bar", "doc_" + i)
            .source(jsonBuilder().startObject().field("foo", "bar").endObject()
    ));
}

bulkProcessor.flush();
client.admin().indices().prepareRefresh("foo").get();
SearchResponse response = client.prepareSearch("foo").get();
// response does not contain any hit
```

The problem is that by default bulkProcessor defines the number of concurrent requests to 1 which is using behind the scene an Async BulkRequestHandler.
When you call `flush()` in a test, you expect it to flush all the content of the bulk so you can search for your docs.
But because of the async handling, there is a great chance that none of the documents has been indexed yet when you call the `refresh` method.

We should advice in our Java guide to explicitly set concurrent requests to `0` so users will use behind the scene the Sync BulkRequestHandler.

```java
BulkProcessor bulkProcessor = BulkProcessor.builder(client, new BulkProcessor.Listener() {
    @Override public void beforeBulk(long executionId, BulkRequest request) {}
    @Override public void afterBulk(long executionId, BulkRequest request, BulkResponse response) {}
    @Override public void afterBulk(long executionId, BulkRequest request, Throwable failure) {}
})
        .setBulkActions(5000)
        .setFlushInterval(TimeValue.timeValueSeconds(10))
        .setConcurrentRequests(0)
        .build();
```

Closes #22158.
2016-12-16 16:45:56 +01:00
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2016-12-14 11:36:55 +01:00
2015-08-01 05:14:46 -04:00