More logging around Apache client creation & close

changelog/@unreleased/pr-655.v2.yml

@@ -0,0 +1,6 @@
+type: improvement
+improvement:
+  description: '`ApacheHttpClientChannels` prints some debug log lines around creation
+    & close'
+  links:
+  - https://github.com/palantir/dialogue/pull/655

dialogue-apache-hc4-client/src/main/java/com/palantir/dialogue/hc4/ApacheHttpClientChannels.java

@@ -73,6 +73,7 @@
 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;
@@ -145,21 +146,37 @@ private static MetricName clientPoolSizeMetricName(String clientName, String sta
 
     /** Intentionally opaque wrapper type - we don't want people using the inner Apache client directly. */
     public static final class CloseableClient implements Closeable {
+        private final String name;
         private final CloseableHttpClient client;
+        private final PoolingHttpClientConnectionManager pool;
         private final ResponseLeakDetector leakDetector;
 
         @Nullable
         private final ExecutorService executor;
 
         CloseableClient(
-                CloseableHttpClient client, ResponseLeakDetector leakDetector, @Nullable ExecutorService executor) {
+                String name,
+                CloseableHttpClient client,
+                PoolingHttpClientConnectionManager pool,
+                ResponseLeakDetector leakDetector,
+                @Nullable ExecutorService executor) {
+            log.debug("Apache client created", SafeArg.of("name", name));
+            this.name = name;
             this.client = client;
+            this.pool = pool;
             this.leakDetector = leakDetector;
             this.executor = executor;
         }
 
         @Override
         public void close() throws IOException {
+            PoolStats poolStats = pool.getTotalStats();
+            log.debug(
+                    "Closing Apache client",
+                    SafeArg.of("name", name),
+                    SafeArg.of("idle", poolStats.getAvailable()),
+                    SafeArg.of("leased", poolStats.getLeased()),
+                    SafeArg.of("pending", poolStats.getPending()));
             client.close();
         }
 
@@ -301,7 +318,11 @@ public CloseableClient build() {
             });
 
             return new CloseableClient(
-                    builder.build(), ResponseLeakDetector.of(name, conf.taggedMetricRegistry()), executor);
+                    name,
+                    builder.build(),
+                    connectionManager,
+                    ResponseLeakDetector.of(name, conf.taggedMetricRegistry()),
+                    executor);
         }
     }