Fix potential memory leaks.

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## Unreleased
 
 * Fix: Do not include stacktrace frames into Timber message (#1898)
+* Fix: Potential memory leaks (#1909)
 
 Breaking changes:
 `Timber.tag` is no longer supported by our [Timber integration](https://docs.sentry.io/platforms/android/configuration/integrations/timber/) and will not appear on Sentry for error events. 

sentry-spring/api/sentry-spring.api

@@ -27,8 +27,9 @@ public class io/sentry/spring/SentryHubRegistrar : org/springframework/context/a
 	public fun registerBeanDefinitions (Lorg/springframework/core/type/AnnotationMetadata;Lorg/springframework/beans/factory/support/BeanDefinitionRegistry;)V
 }
 
-public class io/sentry/spring/SentryInitBeanPostProcessor : org/springframework/beans/factory/config/BeanPostProcessor, org/springframework/context/ApplicationContextAware {
+public class io/sentry/spring/SentryInitBeanPostProcessor : org/springframework/beans/factory/DisposableBean, org/springframework/beans/factory/config/BeanPostProcessor, org/springframework/context/ApplicationContextAware {
 	public fun <init> ()V
+	public fun destroy ()V
 	public fun postProcessAfterInitialization (Ljava/lang/Object;Ljava/lang/String;)Ljava/lang/Object;
 	public fun setApplicationContext (Lorg/springframework/context/ApplicationContext;)V
 }

sentry-spring/src/main/java/io/sentry/spring/SentryInitBeanPostProcessor.java

@@ -10,13 +10,18 @@
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.springframework.beans.BeansException;
+import org.springframework.beans.factory.DisposableBean;
 import org.springframework.beans.factory.config.BeanPostProcessor;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.ApplicationContextAware;
 
-/** Initializes Sentry after all beans are registered. */
+/**
+ * Initializes Sentry after all beans are registered. Closes Sentry on Spring application context
+ * destroy.
+ */
 @Open
-public class SentryInitBeanPostProcessor implements BeanPostProcessor, ApplicationContextAware {
+public class SentryInitBeanPostProcessor
+    implements BeanPostProcessor, ApplicationContextAware, DisposableBean {
   private @Nullable ApplicationContext applicationContext;
 
   @Override
@@ -68,4 +73,9 @@ public void setApplicationContext(final @NotNull ApplicationContext applicationC
       throws BeansException {
     this.applicationContext = applicationContext;
   }
+
+  @Override
+  public void destroy() {
+    Sentry.close();
+  }
 }

sentry/src/main/java/io/sentry/HostnameCache.java

@@ -21,12 +21,18 @@
  * by keeping track of the hostname for a period defined during the construction. For performance
  * purposes, the operation of retrieving the hostname will automatically fail after a period of time
  * defined by {@link #GET_HOSTNAME_TIMEOUT} without result.
+ *
+ * <p>HostnameCache is a singleton and its instance should be obtained through {@link
+ * HostnameCache#getInstance()}.
  */
 final class HostnameCache {
   private static final long HOSTNAME_CACHE_DURATION = TimeUnit.HOURS.toMillis(5);
 
   /** Time before the get hostname operation times out (in ms). */
   private static final long GET_HOSTNAME_TIMEOUT = TimeUnit.SECONDS.toMillis(1);
+
+  @Nullable private static HostnameCache INSTANCE;
+
   /** Time for which the cache is kept. */
   private final long cacheDuration;
   /** Current value for hostname (might change over time). */
@@ -41,7 +47,14 @@ final class HostnameCache {
   private final @NotNull ExecutorService executorService =
       Executors.newSingleThreadExecutor(new HostnameCacheThreadFactory());
 
-  public HostnameCache() {
+  static @NotNull HostnameCache getInstance() {
+    if (INSTANCE == null) {
+      INSTANCE = new HostnameCache();
+    }
+    return INSTANCE;
+  }
+
+  private HostnameCache() {
     this(HOSTNAME_CACHE_DURATION);
   }
 

sentry/src/main/java/io/sentry/MainEventProcessor.java

@@ -34,7 +34,7 @@ public final class MainEventProcessor implements EventProcessor, Closeable {
   private final @Nullable HostnameCache hostnameCache;
 
   MainEventProcessor(final @NotNull SentryOptions options) {
-    this(options, options.isAttachServerName() ? new HostnameCache() : null);
+    this(options, options.isAttachServerName() ? HostnameCache.getInstance() : null);
   }
 
   MainEventProcessor(

sentry/src/main/java/io/sentry/Sentry.java

@@ -237,6 +237,8 @@ private static boolean initConfigurations(final @NotNull SentryOptions options)
   public static synchronized void close() {
     final IHub hub = getCurrentHub();
     mainHub = NoOpHub.getInstance();
+    // remove thread local to avoid memory leak
+    currentHub.remove();
     hub.close();
   }