On Wed, 2018-04-25 at 12:48 +0300, Yossi Tamari wrote:
> Hi Paul,
>
>
>
> Depending on exactly what timeouts you need to change dynamically,
> maybe you
> can use RequestConfig to set it per request instead of per Client?
>
> If not, you could override PoolingHttpClientConnectionManager, add a
> shutdown flag, and override releaseConnection, so that if this flag
> is true,
> it will check if there are any other leased connections (using
> getTotalStats), and if not it will call shutdown(). Then you can stay
> with
> your current approach of creating a new Client, but feel safe that
> you only
> close the previous Client when it is no longer in use.
>
+1 to that
Generally one should only need to modify HttpContext associated with
logically related requests, not HttpClient instance used to execute
them.
Cheers
Oleg
>
>
> Yossi.
>
>
>
> From: Daly, Paul <paul.d...@dieboldnixdorf.com>
> Sent: 25 April 2018 11:12
> To: httpclient-users@hc.apache.org
> Subject: How to replace / update a httpClient instance?
>
>
>
> Hi All,
>
>
>
>
>
> First time poster, hoping you can provide some advice/help!
>
>
>
>
>
> WE have developed a connector to a back end server using HTTP Client.
> The
> component with the HTTPClient runs as part of, and is used by, a
> larger
> application - ie not a standalone application which we have control
> to
> completely change. As per performance optimisations guide I reuse the
> HTTPClient object within this communication component. Its's
> initialised on
> first use and within the running application, the httpClient object
> will be
> passed out to multiple threads who each will execute their own
> particular
> request to the back end. Request objects are reset() by the thread
> which
> used them.
>
>
>
>
>
> So far so good. All seems to work ok.
>
>
>
> However, the application we are running within provides a front end
> for
> users. For admins, this allows changing of various configuration
> items, some
> of which are the timeouts for this component. If an admin changes
> those
> values we want to be able to change the HTTPClient to use the new
> values
> without a restart of the application. The application framework
> provides an
> annotation I can use in my class to pick up config change events. I
> can
> react on that to refresh my timeout values and recreate the client.
>
>
>
> This is where my question starts. My solution so far is to simply
> replace
> the static httpClient with the newly build object which has the new
> timeout
> values. But this may lead to problems because I am not sure if the
> original
> object will actually be tidied up by GC once the threads using it
> have
> closed their connections.
>
>
>
> Ideally I would want to explicitly close the original httpClient
> before
> pointing the static at the new one. However, this means threads which
> have
> already been handed this httpClient reference will fail (user impact
> - not
> acceptable).
>
>
>
> So I am kind of stuck on how to implement this safely
>
>
>
> Ideally I could just change the configured timeouts in the existing
> httpClient but I don't see how to do that.
>
>
>
> Code snippets are below.
>
>
>
> Any ideas / suggestions would be appreciated!
>
>
>
>
>
>
>
>
>
>
>
> /**
>
> * A HTTP Client to be used by the EIS PH
>
> */
>
> private static CloseableHttpClient httpClient = null;
>
>
>
>
>
> // get client
>
> public static CloseableHttpClient getClient() {
>
>
>
> if (httpClient == null) {
>
> // create new client
>
> init(false);
>
> }
>
>
>
> return httpClient;
>
> }
>
>
>
>
>
> // initialize the client
>
> private static synchronized void init(boolean forceNewClient) {
>
>
>
> if (forceNewClient || (httpClient == null)) {
>
>
>
> // get config, timeouts etc from application framework.
>
> ...
>
>
>
> // create the client
>
> CloseableHttpClient newClient =
> HttpClientBuilder.create().useSystemProperties()
>
>
> .setDefaultRequestConfig(config).setMaxConnPerRoute(maxConnectionsPer
> Route)
>
> .setMaxConnTotal(totalMaxConnection).evictExpiredConnect
> ions()
>
> .evictIdleConnections(idleEvictTime, TimeUnit.MINUTES)
>
> .setConnectionTimeToLive(timeToLive,
> TimeUnit.MINUTES).build();
>
>
>
> // set the static member to be the new client now that its built
>
> httpClient = newClient;
>
>
>
> }
>
>
>
>
>
> // listen for application config change events which affect this
> component
>
> @ConfigChangedListener(ConfigurationHelper.OWNER)
>
> public void onConfigChanged() {
>
> init(true);
>
> }
>
>
>
>
>
> Thanks in advance!
>
>
>
> Paul.
>
>
>
>
>
>
>
>
>
> Paul Daly
>
>
>
> Diebold Nixdorf
>
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>
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>
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>
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