104 daemon threads (#105)

* Revert "Update LICENSE"

* Added new option that instructs Tjahzi to use daemon threads (and thus potentially loose data when idle).

* Re #104: Added documentation of useDaemonThreads option to log4j2 and logback. Always using daemon threads for netty event loop group.

* Re #104: Fixed test.

* Re #104: Fixed test.

* Re #104: Added test verifying we start threads as daemons.

* Re #104: Corrected a typo in the docs.

* Re #104: Rewrite of the readme section about useDaemonThreads option.

README.md

@@ -83,5 +83,5 @@ Check out [this wiki article](https://github.com/tkowalcz/tjahzi/wiki/Monitoring
 
 # LICENSE
 
-This work is released under MIT license with the provision that any company registered or conducting operations mainly in Russian Federation IS PROHIBITED from using this software. 
+This work is released under MIT license. Feel free to use, copy and modify this work as long as you credit original authors.
 Pull and feature requests are welcome.

core/src/main/java/pl/tkowalcz/tjahzi/LoggingSystem.java

@@ -13,18 +13,21 @@ public class LoggingSystem {
     private final AgentRunner runner;
 
     private final MonitoringModule monitoringModule;
+    private final boolean useDaemonThreads;
     private final Closeable[] resourcesToCleanup;
 
     public LoggingSystem(
             ManyToOneRingBuffer logBuffer,
             AgentRunner runner,
             MonitoringModule monitoringModule,
+            boolean useDaemonThreads,
             Closeable... resourcesToCleanup
     ) {
         this.logBuffer = logBuffer;
         this.runner = runner;
 
         this.monitoringModule = monitoringModule;
+        this.useDaemonThreads = useDaemonThreads;
         this.resourcesToCleanup = resourcesToCleanup;
     }
 
@@ -33,7 +36,15 @@ public TjahziLogger createLogger() {
     }
 
     public void start() {
-        AgentRunner.startOnThread(runner);
+        AgentRunner.startOnThread(
+                runner,
+                runnable -> {
+                    Thread result = new Thread(runnable);
+                    result.setDaemon(useDaemonThreads);
+
+                    return result;
+                }
+        );
     }
 
     public void close(

core/src/main/java/pl/tkowalcz/tjahzi/TjahziInitializer.java

@@ -25,7 +25,8 @@ public LoggingSystem createLoggingSystem(
             int bufferSizeBytes,
             long logShipperWakeupIntervalMillis,
             long shutdownTimeoutMillis,
-            boolean offHeap
+            boolean offHeap,
+            boolean useDaemonThreads
     ) {
         bufferSizeBytes = findNearestPowerOfTwo(bufferSizeBytes);
         ByteBuffer javaBuffer = allocateJavaBuffer(bufferSizeBytes, offHeap);
@@ -64,6 +65,7 @@ public LoggingSystem createLoggingSystem(
                 logBuffer,
                 runner,
                 monitoringModule,
+                useDaemonThreads,
                 httpClient
         );
     }

core/src/main/java/pl/tkowalcz/tjahzi/http/HttpConnection.java

@@ -3,6 +3,7 @@
 import io.netty.channel.ChannelFuture;
 import io.netty.channel.nio.NioEventLoopGroup;
 import io.netty.handler.codec.http.FullHttpRequest;
+import io.netty.util.concurrent.DefaultThreadFactory;
 import pl.tkowalcz.tjahzi.stats.MonitoringModule;
 
 import java.io.Closeable;
@@ -20,9 +21,7 @@ public HttpConnection(ClientConfiguration clientConfiguration, MonitoringModule
         this.clientConfiguration = clientConfiguration;
         this.monitoringModule = monitoringModule;
 
-        ThreadGroup threadGroup = new ThreadGroup("Tjahzi Loki client");
-        ThreadFactory threadFactory = r -> new Thread(threadGroup, r, "tjahzi-worker");
-
+        ThreadFactory threadFactory = new DefaultThreadFactory("tjahzi-worker", true);
         this.group = new NioEventLoopGroup(1, threadFactory);
 
         EventLoopGroupRetry retry = new EventLoopGroupRetry(

core/src/test/java/pl/tkowalcz/tjahzi/HeadersTest.java

@@ -91,6 +91,7 @@ void shouldIncludeAdditionalHeaders() {
                 1024 * 1024,
                 250,
                 10_000,
+                false,
                 false
         );
         loggingSystem.start();
@@ -145,6 +146,7 @@ void shouldHandleCaseWithNoAdditionalHeaders() {
                 1024 * 1024,
                 250,
                 10_000,
+                false,
                 false
         );
         loggingSystem.start();
@@ -201,6 +203,7 @@ void shouldNotOverrideCrucialHeaders() {
                 1024 * 1024,
                 250,
                 10_000,
+                false,
                 false
         );
         loggingSystem.start();

core/src/test/java/pl/tkowalcz/tjahzi/LoggingSystemSanityCheckTest.java

@@ -69,6 +69,7 @@ void setUp() {
                 1024 * 1024,
                 250,
                 10_000,
+                false,
                 false
         );
 

core/src/test/java/pl/tkowalcz/tjahzi/LoggingSystemTest.java

@@ -73,6 +73,7 @@ void setUp() {
                 0,
                 250,
                 10_000,
+                false,
                 false
         );
 

core/src/test/java/pl/tkowalcz/tjahzi/ReconnectTest.java

@@ -86,6 +86,7 @@ void shouldEventuallyReconnectIfLokiWasDownWhenStarting() {
                 1024 * 1024,
                 250,
                 10_000,
+                false,
                 false
         );
         loggingSystem.start();
@@ -138,6 +139,7 @@ void shouldReconnectIfLokiFailed() {
                 1024 * 1024,
                 250,
                 10_000,
+                false,
                 false
         );
         loggingSystem.start();

core/src/test/java/pl/tkowalcz/tjahzi/ResourcesCleanupOnCloseTest.java

@@ -14,7 +14,9 @@
 import java.lang.management.ManagementFactory;
 import java.lang.management.ThreadInfo;
 import java.lang.management.ThreadMXBean;
+import java.util.Arrays;
 import java.util.Map;
+import java.util.Optional;
 import java.util.concurrent.TimeUnit;
 
 import static com.github.tomakehurst.wiremock.core.WireMockConfiguration.wireMockConfig;
@@ -26,6 +28,7 @@ class ResourcesCleanupOnCloseTest {
     private WireMockServer wireMockServer;
     private TjahziInitializer initializer;
     private StandardMonitoringModule monitoringModule;
+    private LoggingSystem loggingSystem;
 
     @BeforeEach
     void setUp() {
@@ -43,6 +46,13 @@ void setUp() {
     @AfterEach
     void tearDown() {
         wireMockServer.stop();
+
+        if (loggingSystem != null) {
+            loggingSystem.close(
+                    (int) TimeUnit.SECONDS.toMillis(10),
+                    System.out::println
+            );
+        }
     }
 
     @Test
@@ -72,6 +82,7 @@ void shouldStopThreads() {
                 1024 * 1024,
                 250,
                 10_000,
+                false,
                 false
         );
         loggingSystem.start();
@@ -83,10 +94,8 @@ void shouldStopThreads() {
 
             assertThat(threadInfos)
                     .extracting(ThreadInfo::getThreadName)
-                    .contains(
-                            "LogShipper",
-                            "tjahzi-worker"
-                    );
+                    .anyMatch(threadName -> threadName.contains("LogShipper"))
+                    .anyMatch(threadName -> threadName.contains("tjahzi-worker"));
         });
 
         //When
@@ -108,4 +117,58 @@ void shouldStopThreads() {
                     );
         });
     }
+
+    @Test
+    void shouldStartThreadsAsDaemon() {
+        // Given
+        ClientConfiguration clientConfiguration = ClientConfiguration.builder()
+                .withConnectionTimeoutMillis(10_000)
+                .withHost("localhost")
+                .withPort(wireMockServer.port())
+                .withMaxRetries(1)
+                .build();
+
+        NettyHttpClient httpClient = HttpClientFactory.defaultFactory()
+                .getHttpClient(
+                        clientConfiguration,
+                        monitoringModule,
+                        "X-Scope-OrgID", "Circus",
+                        "C", "Control"
+                );
+
+        // When
+        loggingSystem = initializer.createLoggingSystem(
+                httpClient,
+                monitoringModule,
+                Map.of(),
+                0,
+                0,
+                1024 * 1024,
+                250,
+                10_000,
+                false,
+                true
+        );
+        loggingSystem.start();
+
+        // Then
+        Awaitility.await().untilAsserted(() -> {
+            ThreadMXBean threadMXBean = ManagementFactory.getThreadMXBean();
+            ThreadInfo[] threadInfos = threadMXBean.dumpAllThreads(false, false);
+
+            Optional<ThreadInfo> maybeLogShipper = Arrays.stream(threadInfos)
+                    .filter(thread -> thread.getThreadName().contains("LogShipper"))
+                    .findAny();
+
+            Optional<ThreadInfo> maybeTjahziWorker = Arrays.stream(threadInfos)
+                    .filter(thread -> thread.getThreadName().contains("tjahzi-worker"))
+                    .findAny();
+
+            assertThat(maybeLogShipper)
+                    .hasValueSatisfying(ThreadInfo::isDaemon);
+
+            assertThat(maybeTjahziWorker)
+                    .hasValueSatisfying(ThreadInfo::isDaemon);
+        });
+    }
 }

log4j2-appender/README.md

@@ -356,3 +356,11 @@ controls how often it wakes up to perform its duties. Other properties control h
 
 On logging system shutdown (or config reload) Tjahzi will flush its internal buffers so that no logs are lost. This
 property sets limit on how long to wait for this to complete before proceeding with shutdown.
+
+#### useDaemonThreads (optional, default = false)
+
+If set to true Tjahzi will run all it's threads as daemon threads. 
+
+Use this option if you do not want to explicitly close the logging system and still want to make sure Tjahzi internal 
+threads will not prevent JVM from closing down. Note that this can result in unflushed logs not being delivered when the
+JVM is closed.

log4j2-appender/src/main/java/pl/tkowalcz/tjahzi/log4j2/LokiAppenderBuilder.java

@@ -50,6 +50,9 @@ public class LokiAppenderBuilder<B extends LokiAppenderBuilder<B>> extends Abstr
     @PluginBuilderAttribute
     private boolean useSSL;
 
+    @PluginBuilderAttribute
+    private boolean useDaemonThreads;
+
     @PluginBuilderAttribute
     private String username;
 
@@ -155,7 +158,8 @@ public LokiAppender build() {
                 bufferSizeBytes,
                 logShipperWakeupIntervalMillis,
                 TimeUnit.SECONDS.toMillis(shutdownTimeoutSeconds),
-                isUseOffHeapBuffer()
+                isUseOffHeapBuffer(),
+                useDaemonThreads
         );
 
         int maxLogLineSizeBytes = Math.toIntExact(getMaxLogLineSizeKilobytes() * BYTES_IN_KILOBYTE);
@@ -201,6 +205,14 @@ public void setUseSSL(boolean useSSL) {
         this.useSSL = useSSL;
     }
 
+    public boolean isUseDaemonThreads() {
+        return useDaemonThreads;
+    }
+
+    public void setUseDaemonThreads(boolean useDaemonThreads) {
+        this.useDaemonThreads = useDaemonThreads;
+    }
+
     public String getUsername() {
         return username;
     }

log4j2-appender/src/test/java/pl/tkowalcz/tjahzi/log4j2/GrafanaCloudAppenderTest.java

@@ -3,6 +3,7 @@
 import org.apache.commons.lang3.RandomStringUtils;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
+import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 
 import static org.hamcrest.CoreMatchers.*;
@@ -12,6 +13,7 @@
 class GrafanaCloudAppenderTest {
 
     @Test
+    @Disabled
     void shouldSendData() {
         // Given
         System.setProperty("loki.host", "logs-prod-us-central1.grafana.net");