Connection leak with flink elastic Sink

[Vijay Bhaskar]

Hi
We are using flink elastic sink which streams at the rate of 1000
events/sec, as described in
https://ci.apache.org/projects/flink/flink-docs-stable/dev/connectors/elasticsearch.html
.
We are observing connection leak of elastic connections. After few minutes
all the open connections are exceeding the process limits of the max open
descriptors and Job is getting terminated. But the  http connections with
the elastic search server remain open forever. Am i missing any specific
configuration setting to close the open connection, after serving the
request?
But there is no such setting is described in the above documentation of
elastic sink

Regards
Bhaskar

[Chesnay Schepler-3]

Specifically which connector are you using, and which Flink version?

On 12.12.2018 13:31, Vijay Bhaskar wrote:

> Hi
> We are using flink elastic sink which streams at the rate of 1000
> events/sec, as described in
> https://ci.apache.org/projects/flink/flink-docs-stable/dev/connectors/elasticsearch.html.
> We are observing connection leak of elastic connections. After few
> minutes all the open connections are exceeding the process limits of
> the max open descriptors and Job is getting terminated. But the  http
> connections with the elastic search server remain open forever. Am i
> missing any specific configuration setting to close the open
> connection, after serving the request?
> But there is no such setting is described in the above documentation
> of elastic sink
>
> Regards
> Bhaskar

[Tzu-Li (Gordon) Tai]

Hi,

Besides the information that Chesnay requested, could you also provide a stack trace of the exception that caused the job to terminate in the first place?

The Elasticsearch sink does indeed close the internally used Elasticsearch client, which should in turn properly release all resources [1].
I would like to double check whether or not the case here is that that part of the code was never reached.

Cheers,
Gordon

[1] https://github.com/apache/flink/blob/master/flink-connectors/flink-connector-elasticsearch-base/src/main/java/org/apache/flink/streaming/connectors/elasticsearch/ElasticsearchSinkBase.java#L334

On 13 December 2018 at 5:59:34 PM, Chesnay Schepler ([hidden email]) wrote:

Specifically which connector are you using, and which Flink version?  

On 12.12.2018 13:31, Vijay Bhaskar wrote:  

> Hi  
> We are using flink elastic sink which streams at the rate of 1000  
> events/sec, as described in  
> https://ci.apache.org/projects/flink/flink-docs-stable/dev/connectors/elasticsearch.html.  
> We are observing connection leak of elastic connections. After few  
> minutes all the open connections are exceeding the process limits of  
> the max open descriptors and Job is getting terminated. But the http  
> connections with the elastic search server remain open forever. Am i  
> missing any specific configuration setting to close the open  
> connection, after serving the request?  
> But there is no such setting is described in the above documentation  
> of elastic sink  
>  
> Regards  
> Bhaskar  

[Vijay Bhaskar]

Hi Gordon,

We are using flink cluster 1.6.1, elastic search connector version: flink-connector-elasticsearch6_2.11

Attached the stack trace. 

Following are the max open file descriptor limit of theTask manager  process and open connections to the elastic

search cluster

Regards

Bhaskar

#lsof -p 62041 | wc -l

65583

All the connections to elastic cluster reached to:

netstat -aln | grep 9200 | wc -l

2333

On Thu, Dec 13, 2018 at 4:12 PM Tzu-Li (Gordon) Tai <[hidden email]> wrote:

Hi,

Besides the information that Chesnay requested, could you also provide a stack trace of the exception that caused the job to terminate in the first place?

The Elasticsearch sink does indeed close the internally used Elasticsearch client, which should in turn properly release all resources [1].

I would like to double check whether or not the case here is that that part of the code was never reached.

Cheers,

Gordon

[1] https://github.com/apache/flink/blob/master/flink-connectors/flink-connector-elasticsearch-base/src/main/java/org/apache/flink/streaming/connectors/elasticsearch/ElasticsearchSinkBase.java#L334

On 13 December 2018 at 5:59:34 PM, Chesnay Schepler ([hidden email]) wrote:

Specifically which connector are you using, and which Flink version?

On 12.12.2018 13:31, Vijay Bhaskar wrote:

> Hi
> We are using flink elastic sink which streams at the rate of 1000
> events/sec, as described in
> https://ci.apache.org/projects/flink/flink-docs-stable/dev/connectors/elasticsearch.html.
> We are observing connection leak of elastic connections. After few
> minutes all the open connections are exceeding the process limits of
> the max open descriptors and Job is getting terminated. But the http
> connections with the elastic search server remain open forever. Am i
> missing any specific configuration setting to close the open
> connection, after serving the request?
> But there is no such setting is described in the above documentation
> of elastic sink
>
> Regards
> Bhaskar