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(maxConnectionsPerRoute)
.setMaxConnTotal(totalMaxConnection).evictExpiredConnections()
.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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