[jira] [Work started] (KNOX-807) Missing resource deallocation

["Vincent Devillers (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/KNOX-807?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Work on KNOX-807 started by Vincent Devillers.
----------------------------------------------
> Missing resource deallocation
> -----------------------------
>
>                 Key: KNOX-807
>                 URL: https://issues.apache.org/jira/browse/KNOX-807
>             Project: Apache Knox
>          Issue Type: Bug
>          Components: ClientDSL
>            Reporter: Vincent Devillers
>            Assignee: Vincent Devillers
>              Labels: KIP-4
>             Fix For: 0.12.0
>
>         Attachments: KNOX-807.patch
>
>
> h2. Release connection to pool after HTTP call
> The close() method in BasicResponse does only EntityUtils.consumeQuietly(response.getEntity()):
> {code}
>     public void close() {
>         this.consume();
>     }
>     public void consume() {
>         if(!this.consumed) {
>             EntityUtils.consumeQuietly(this.response.getEntity());
>             this.consumed = true;
>         }
>     }
> {code}
> The underlying HTTP connection is still held. In order to ensure correct deallocation of OS resources we need to call CloseableHttpResponse#close() like this:
> {code}
> public void close() {
>     try {
>         this.consume();
>     } finally {
>         if (response instanceof CloseableHttpResponse) {
>             try {
>                 ((CloseableHttpResponse) response).close();
>             } catch (IOException e) {
>                 throw Throwables.propagate(e);
>             }
>         }
>     }
> }
> {code}
> h2. Shutdown connection pool
> Also when the Hadoop session is no more used, the only method present by to be call is shutdown(), but it close only the ExecutorService. When a CloseableHttpClient instance is no longer needed, we have to shut down the connection manager to ensure immediate deallocation of all OS resources.
> {code}
> public void close() {
>     try {
>       executor.shutdownNow();
>     } catch(Exception e) {
>       // log something here
>     }
>     try {
>       client.close();
>       // client.close() should call getConnectionManager().shutdown();
>     } catch(Exception e) {
>       // log something here
>     }
> }
> {code}
> [Source|https://blog.layer4.fr/2016/12/06/knox-production-pitfalls-and-common-mistakes/]



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