From: gu.martinm@gmail.com <gu.martinm@gmail.com>
Date: Thu, 9 Oct 2014 16:31:53 +0000 (+0200)
Subject: Data base deadlocks. How to deal with them (retries)
X-Git-Url: https://git.gumartinm.name/?a=commitdiff_plain;h=6305efd94dddbfff9108b9d17ef812d4bcbe23ee;p=JavaForFun

Data base deadlocks. How to deal with them (retries)
---

diff --git a/SpringJava/DeadLocksSQL/src/main/java/de/example/sql/deadlocks/Main.java b/SpringJava/DeadLocksSQL/src/main/java/de/example/sql/deadlocks/Main.java
index 80ef633..7ba468c 100644
--- a/SpringJava/DeadLocksSQL/src/main/java/de/example/sql/deadlocks/Main.java
+++ b/SpringJava/DeadLocksSQL/src/main/java/de/example/sql/deadlocks/Main.java
@@ -17,10 +17,11 @@ public class Main {
 	public static void main(String[] args) {
 		final ThreadGate trx1Gate = new ThreadGate();
 		final ThreadGate trx2Gate = new ThreadGate();
+		final FutureTask<Void>[] tasks = new FutureTask[2];
 
 		logger.info("Starting application");
 
-		final FutureTask<Void> taskFirst = new FutureTask<Void>
+		tasks[0] = new FutureTask<Void>
 		(
 			new Runnable(){
 
@@ -34,7 +35,7 @@ public class Main {
 			},
 			null
 		);
-		final FutureTask<Void> taskSecond = new FutureTask<Void>
+		tasks[1] = new FutureTask<Void>
 		(
 			new Runnable(){
 
@@ -49,20 +50,24 @@ public class Main {
 			null
 		);
 
-		new Thread(taskFirst).start();
-		new Thread(taskSecond).start();
+		for (final FutureTask<Void> task : tasks) {
+			new Thread(task).start();
+		}
 
 		// Wait for end.
-		try {
-			taskFirst.get();
-			taskSecond.get();
-		} catch (final InterruptedException e) {
-			logger.error("Error", e);
-		} catch (final ExecutionException e) {
-			logger.error("Error", e);
+		for (final FutureTask<Void> task : tasks) {
+			try {
+				task.get();
+			} catch (final InterruptedException e) {
+				logger.error("Error", e);
+			} catch (final ExecutionException e) {
+				logger.error("Error", e);
+			} finally {
+				task.cancel(true);
+			}
 		}
 
-
+		SpringContextLocator.getInstance().close();
 		logger.info("End application");
 	}
 }
diff --git a/SpringJava/DeadLocksSQL/src/main/java/de/example/sql/deadlocks/SpringContextLocator.java b/SpringJava/DeadLocksSQL/src/main/java/de/example/sql/deadlocks/SpringContextLocator.java
index 36bdda1..0c8a8a8 100644
--- a/SpringJava/DeadLocksSQL/src/main/java/de/example/sql/deadlocks/SpringContextLocator.java
+++ b/SpringJava/DeadLocksSQL/src/main/java/de/example/sql/deadlocks/SpringContextLocator.java
@@ -2,7 +2,6 @@ package de.example.sql.deadlocks;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
-import org.springframework.context.ApplicationContext;
 import org.springframework.context.support.ClassPathXmlApplicationContext;
 
 
@@ -11,7 +10,7 @@ public final class SpringContextLocator {
 	// Spring Context
 	private static final String SPRING_CONFIG_CONTEXT="/spring-config.xml";
 	// Spring ApplicationContext
-	private final ApplicationContext context;
+	private final ClassPathXmlApplicationContext context;
 	
 	
 	private SpringContextLocator() {
@@ -34,4 +33,8 @@ public final class SpringContextLocator {
 	public Object getBean(final String name) {
 		return context.getBean(name);
 	}
+
+	public void close() {
+		context.close();
+	}
 }
diff --git a/SpringJava/DeadLocksSQL/src/main/java/de/example/sql/deadlocks/example/FirstTransaction.java b/SpringJava/DeadLocksSQL/src/main/java/de/example/sql/deadlocks/example/FirstTransaction.java
index 08472ec..23d72a5 100644
--- a/SpringJava/DeadLocksSQL/src/main/java/de/example/sql/deadlocks/example/FirstTransaction.java
+++ b/SpringJava/DeadLocksSQL/src/main/java/de/example/sql/deadlocks/example/FirstTransaction.java
@@ -30,7 +30,7 @@ public class FirstTransaction {
 		}
     }
 
-    public void doFirstStepWithGate() {
+    private void doFirstStepWithGate() {
 		logger.info("Start doFirstStepWithGate");
 
 		logger.info("doFirstStepWithGate UPDATING");
@@ -56,7 +56,7 @@ public class FirstTransaction {
         logger.info("End doFirstStepWithGate");
     }
 
-    public void doFirstStepWithoutGate() {
+    private void doFirstStepWithoutGate() {
 		logger.info("Start doFirstStepWithoutGate");
 
 		logger.info("doFirstStepWithoutGate UPDATING");
@@ -77,8 +77,6 @@ public class FirstTransaction {
 		final JdbcOperations jdbcTemplate = new JdbcTemplate(dataSource);
 		jdbcTemplate.execute("UPDATE children SET name='Bob', parent_id='1' WHERE id='2'");
 
-		// trx2 continues  (fourth step)
-
         logger.info("End doThirdStep");
     }