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Apache connection pool instrumentation #457

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6 changes: 6 additions & 0 deletions changelog/@unreleased/pr-457.v2.yml
Original file line number Diff line number Diff line change
@@ -0,0 +1,6 @@
type: improvement
improvement:
description: Each closeable apache client now exposes methods which reveal statistics
about the connection pool.
links:
- https://github.com/palantir/dialogue/pull/457
Original file line number Diff line number Diff line change
Expand Up @@ -59,14 +59,18 @@
import org.apache.http.client.config.RequestConfig;
import org.apache.http.config.RegistryBuilder;
import org.apache.http.config.SocketConfig;
import org.apache.http.conn.socket.ConnectionSocketFactory;
import org.apache.http.conn.socket.PlainConnectionSocketFactory;
import org.apache.http.conn.ssl.DefaultHostnameVerifier;
import org.apache.http.conn.ssl.SSLConnectionSocketFactory;
import org.apache.http.impl.auth.BasicSchemeFactory;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.impl.client.ProxyAuthenticationStrategy;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
import org.apache.http.impl.conn.SystemDefaultRoutePlanner;
import org.apache.http.pool.PoolStats;
import org.apache.http.protocol.HttpContext;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
Expand Down Expand Up @@ -96,6 +100,26 @@ public static CloseableClient createCloseableHttpClient(ClientConfiguration conf
long socketTimeoutMillis =
Math.max(conf.readTimeout().toMillis(), conf.writeTimeout().toMillis());
int connectTimeout = Ints.checkedCast(conf.connectTimeout().toMillis());

SocketConfig socketConfig = SocketConfig.custom().setSoKeepAlive(true).build();
SSLConnectionSocketFactory sslSocketFactory = new SSLConnectionSocketFactory(
conf.sslSocketFactory(),
new String[] {"TLSv1.2"},
conf.enableGcmCipherSuites()
? jvmSupportedCipherSuites(CipherSuites.allCipherSuites())
: jvmSupportedCipherSuites(CipherSuites.fastCipherSuites()),
new DefaultHostnameVerifier());

PoolingHttpClientConnectionManager connectionManager = new PoolingHttpClientConnectionManager(
RegistryBuilder.<ConnectionSocketFactory>create()
.register("http", PlainConnectionSocketFactory.getSocketFactory())
.register("https", sslSocketFactory)
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I wonder if we can wrap these to add a meter of connection rate, and wrap the pool manager to capture the rate connections requested?

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Mmm that would be cool, so dividing one by the other tells us how effectively we're re-using... Do we not already get that connection rate from the tritium tls.handshakes?

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Tritium handshake instrumentation would work assuming https, but I don’t think we wire it up yet.

.build());

connectionManager.setDefaultSocketConfig(socketConfig);
connectionManager.setMaxTotal(Integer.MAX_VALUE);
connectionManager.setDefaultMaxPerRoute(Integer.MAX_VALUE);

HttpClientBuilder builder = HttpClients.custom()
.setDefaultRequestConfig(RequestConfig.custom()
.setSocketTimeout(Ints.checkedCast(socketTimeoutMillis))
Expand All @@ -106,11 +130,10 @@ public static CloseableClient createCloseableHttpClient(ClientConfiguration conf
.setRedirectsEnabled(false)
.setRelativeRedirectsAllowed(false)
.build())
.setDefaultSocketConfig(
SocketConfig.custom().setSoKeepAlive(true).build())
.setDefaultSocketConfig(socketConfig)
.evictIdleConnections(55, TimeUnit.SECONDS)
.setMaxConnPerRoute(Integer.MAX_VALUE)
.setMaxConnTotal(Integer.MAX_VALUE)
.setConnectionManagerShared(false) // will be closed when the client is closed
.setConnectionManager(connectionManager)
// TODO(ckozak): proxy credentials
.setRoutePlanner(new SystemDefaultRoutePlanner(null, conf.proxy()))
.disableAutomaticRetries()
Expand All @@ -120,14 +143,7 @@ public static CloseableClient createCloseableHttpClient(ClientConfiguration conf
.disableCookieManagement()
// Dialogue handles content-compression with ContentDecodingChannel
.disableContentCompression()
.setSSLSocketFactory(
new SSLConnectionSocketFactory(
conf.sslSocketFactory(),
new String[] {"TLSv1.2"},
conf.enableGcmCipherSuites()
? jvmSupportedCipherSuites(CipherSuites.allCipherSuites())
: jvmSupportedCipherSuites(CipherSuites.fastCipherSuites()),
new DefaultHostnameVerifier()))
.setSSLSocketFactory(sslSocketFactory)
.setDefaultCredentialsProvider(NullCredentialsProvider.INSTANCE)
.setTargetAuthenticationStrategy(NullAuthenticationStrategy.INSTANCE)
.setProxyAuthenticationStrategy(NullAuthenticationStrategy.INSTANCE)
Expand All @@ -141,15 +157,17 @@ public static CloseableClient createCloseableHttpClient(ClientConfiguration conf
.build());
});

return new CloseableClient(builder.build());
return new CloseableClient(builder.build(), connectionManager);
}

/** Intentionally opaque wrapper type - we don't want people using the inner Apache client directly. */
public static final class CloseableClient implements Closeable {
private final CloseableHttpClient client;
private final PoolingHttpClientConnectionManager connectionManager;

CloseableClient(CloseableHttpClient client) {
CloseableClient(CloseableHttpClient client, PoolingHttpClientConnectionManager connectionManager) {
this.client = client;
this.connectionManager = connectionManager;
}

@Override
Expand All @@ -161,6 +179,14 @@ public void close() throws IOException {
public String toString() {
return "CloseableClient{client=" + client + '}';
}

public PoolStats getPoolStats() {
return connectionManager.getTotalStats();
}

public int getNumRoutes() {
return connectionManager.getRoutes().size();
}
}

/**
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,7 @@
*/
package com.palantir.dialogue.hc4;

import static org.assertj.core.api.Assertions.assertThat;
import static org.assertj.core.api.Assertions.assertThatThrownBy;

import com.google.common.util.concurrent.Futures;
Expand Down Expand Up @@ -58,6 +59,26 @@ public void close_works() throws Exception {
assertThatThrownBy(() -> again.get()).hasMessageContaining("Connection pool shut down");
}

@Test
public void metrics() throws Exception {
ClientConfiguration conf = TestConfigurations.create("http://unused");

try (ApacheHttpClientChannels.CloseableClient client =
ApacheHttpClientChannels.createCloseableHttpClient(conf)) {

Channel channel = ApacheHttpClientChannels.createSingleUri("http://neverssl.com", client);
ListenableFuture<Response> response =
channel.execute(new TestEndpoint(), Request.builder().build());
assertThat(Futures.getUnchecked(response).code()).isEqualTo(200);

assertThat(client.getNumRoutes()).describedAs("routes").isEqualTo(1);
assertThat(client.getPoolStats().getAvailable())
.describedAs("available")
.isEqualTo(0);
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I think graphing the number available will be kinda interesting, as this should tell us how quickly we could handle bursts of traffic

 /**
     * Gets the number idle persistent connections.
     * <p>
     * The total number of connections in the pool is equal to {@code available} plus {@code leased}.
     * </p>
     *
     * @return number idle persistent connections.
     */
    public int getAvailable() {

assertThat(client.getPoolStats().getLeased()).describedAs("leased").isEqualTo(1);
}
}

private static final class TestEndpoint implements Endpoint {
@Override
public void renderPath(Map<String, String> _params, UrlBuilder _url) {}
Expand Down