# Input blocking when output is unavailable

**URL:** <https://discuss.elastic.co/t/input-blocking-when-output-is-unavailable/227661>\
**Category:** Logstash\
**Created:** [April 12, 2020, 9:47am UTC](https://discuss.elastic.co/t/input-blocking-when-output-is-unavailable/227661 "2020-04-12T09:47:34Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![orweinberger](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/orweinberger/32/580_2.png) [@orweinberger](https://discuss.elastic.co/u/orweinberger)\
**Post date:** [April 12, 2020, 9:47am UTC](https://discuss.elastic.co/t/input-blocking-when-output-is-unavailable/227661/1 "2020-04-12T09:47:34Z")

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I have a TCP input that receives messages, a few filters and a single Elasticsearch output. I'm running a small script that sends messages to the LS TCP port every X miliseconds.

After experimenting a bit, I have a few questions:

1. Since Logstash persistent queues does not support TCP inputs, is there any mechanism (other than a message queue) that I can implement to 'guard' myself from long lasting ES downtime?

2. I assumed that if Elasticsearch is down, messages will be stored in-memory, however this is not reflected when I curl `http://localhost:9600/_node/stats/pipelines`, the `pipelines.main.events.in` count stops climbing as soon as ES is down, is there another place I should look for to see the in-memory queue count?

3. I've used the redis output in the past and it has a `congestion_threshold` parameter, is it possible to theoretically implement the same in the elasticsearch output? Does that even block the input, or just blocks the output?

Thanks!

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<div class="post-metadata">

**Author:** ![orweinberger](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/orweinberger/32/580_2.png) [@orweinberger](https://discuss.elastic.co/u/orweinberger)\
**Post date:** [April 16, 2020, 5:25am UTC](https://discuss.elastic.co/t/input-blocking-when-output-is-unavailable/227661/2 "2020-04-16T05:25:26Z")

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bump

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<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [May 14, 2020, 5:25am UTC](https://discuss.elastic.co/t/input-blocking-when-output-is-unavailable/227661/3 "2020-05-14T05:25:27Z")

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