"ConcurrentModificationException"更新我的实体时 [英] "ConcurrentModificationException" when updating my entities
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问题描述
问题
我正在使用hibernate 5.4.11内核，当我尝试更新大量实体时，我在这里遇到了这个问题.它看起来像一个休眠的内部异常.
更新
我使用休眠5.4.23对其进行了测试，发生了相同的异常. 我也将"mysql连接器"更新为最新版本"8.0.22"，但也没有起作用，同样的异常.描述
这是我更新实体的方式，它在另一个线程中运行，这在这里应该不是问题...它基本上是数据库操作的一个自己的线程，在该操作期间没有其他数据库操作在运行.
// Run the database operation for updating the entities async in a new thread, return updated entities once done
return CompletableFuture.runAsync(() -> {
var session = database.openSession();
session.beginTransaction();
try {
// Save identities first
for (var identity : identities)
session.update(identity);
// Update components, each component-type
for(var insertedClass : insertationOrder)
for (var hbc : componentsPerType.get(insertedClass))
session.update(hbc);
session.flush();
session.clear();
session.getTransaction().commit();
} catch (Exception e){
var messageComposer = new ExceptionMessageComposer(e);
GameExtension.getInstance().trace("Update : "+messageComposer.toString());
session.getTransaction().rollback();
}
session.close();
}).thenApply(v -> entities);
我尝试保存的课程
@Entity
@Table(name = "chunk", uniqueConstraints = {@UniqueConstraint(columnNames={"x", "y"})}, indexes = {@Index(columnList = "x,y")})
@Access(value = AccessType.FIELD)
@SelectBeforeUpdate(false)
public class Chunk extends HibernateComponent{
public int x;
public int y;
public Date createdOn;
@OneToMany(fetch = FetchType.EAGER)
@JoinTable(name = "chunk_identity", joinColumns = @JoinColumn(name = "identity_id"), inverseJoinColumns = @JoinColumn(name = "id"), inverseForeignKey = @ForeignKey(ConstraintMode.NO_CONSTRAINT))
@Fetch(FetchMode.JOIN)
@BatchSize(size = 50)
public Set<Identity> inChunk = new LinkedHashSet<>();
@Transient
public Set<ChunkLoader> loadedBy = new LinkedHashSet<>();
public Chunk() {}
public Chunk(int x, int y, Date createdOn) {
this.x = x;
this.y = y;
this.createdOn = createdOn;
}
}
@Entity
@Table(name = "location")
@Access(AccessType.FIELD)
public class Transform extends HibernateComponent {
@Embedded
public Vector2 position = new Vector2();
@ManyToOne
@JoinColumn(name = "chunk_id", referencedColumnName = "identity_id", updatable = false)
@Fetch(FetchMode.JOIN)
public Chunk chunk;
@Transient
public Vector2 previousPos = new Vector2();
public Transform() {}
public Transform(Vector2 position) { this.position = position; }
public Transform(Vector2 position, Chunk chunk) { this.position = position; this.chunk = chunk; }
}
我得到的例外情况
19:29:05,126 INFO [ForkJoinPool.commonPool-worker-19] Extensions - {Game}: Update : java.util.ConcurrentModificationException:
::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
Exception: java.util.ConcurrentModificationException
Message: *** Null ***
+--- --- ---+
Stack Trace:
+--- --- ---+
java.base/java.util.HashMap$HashIterator.nextNode(HashMap.java:1493)
java.base/java.util.HashMap$KeyIterator.next(HashMap.java:1516)
org.hibernate.persister.collection.AbstractCollectionPersister.insertRows(AbstractCollectionPersister.java:1555)
org.hibernate.action.internal.CollectionUpdateAction.execute(CollectionUpdateAction.java:89)
org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:604)
org.hibernate.engine.spi.ActionQueue.lambda$executeActions$1(ActionQueue.java:478)
java.base/java.util.LinkedHashMap.forEach(LinkedHashMap.java:684)
org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:475)
org.hibernate.event.internal.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:348)
org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:40)
org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:102)
org.hibernate.internal.SessionImpl.doFlush(SessionImpl.java:1356)
org.hibernate.internal.SessionImpl.flush(SessionImpl.java:1343)
com.parallelorigin.persistence.database.ECSDatabase.lambda$updateEntities$16(ECSDatabase.java:242)
java.base/java.util.concurrent.CompletableFuture$AsyncRun.run(CompletableFuture.java:1736)
java.base/java.util.concurrent.CompletableFuture$AsyncRun.exec(CompletableFuture.java:1728)
java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:290)
java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1020)
java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1656)
java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1594)
java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:177)
::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
任何人都知道为什么冬眠会抛出该内部异常以及我该怎么做才能解决此问题?
解决方案
您不应更改在其他线程正在处理的情况下持久/更新的entities，identities或components的列表. /p>
持久化/更新实体的线程必须拥有实体对象，即，在事务运行时，没有其他线程可以干扰状态.交易完成后，您只能再次使用这些对象.
我不知道您的应用程序做什么，但是如果您需要访问主线程中的对象，则可以复制对象以进行刷新操作.这样，执行刷新的线程将正确拥有对象并可以安全地对其进行处理.
Problem
Im using hibernate 5.4.11 core and when i try to update large amounts of entities i run into that issue right here. It looks like an hibernate internal exception.
Update
I tested it with hibernate 5.4.23, the same exception occured. I also updated my "mysql connector" to the latest version "8.0.22" and it didnt worked either, the same exception.Describtion
This is how i update my entities, it runs in another thread, which should not be the problem here... its basically a own thread for database operations, during that operation no other database operations are running.
// Run the database operation for updating the entities async in a new thread, return updated entities once done
return CompletableFuture.runAsync(() -> {
var session = database.openSession();
session.beginTransaction();
try {
// Save identities first
for (var identity : identities)
session.update(identity);
// Update components, each component-type
for(var insertedClass : insertationOrder)
for (var hbc : componentsPerType.get(insertedClass))
session.update(hbc);
session.flush();
session.clear();
session.getTransaction().commit();
} catch (Exception e){
var messageComposer = new ExceptionMessageComposer(e);
GameExtension.getInstance().trace("Update : "+messageComposer.toString());
session.getTransaction().rollback();
}
session.close();
}).thenApply(v -> entities);
The class i try to save
@Entity
@Table(name = "chunk", uniqueConstraints = {@UniqueConstraint(columnNames={"x", "y"})}, indexes = {@Index(columnList = "x,y")})
@Access(value = AccessType.FIELD)
@SelectBeforeUpdate(false)
public class Chunk extends HibernateComponent{
public int x;
public int y;
public Date createdOn;
@OneToMany(fetch = FetchType.EAGER)
@JoinTable(name = "chunk_identity", joinColumns = @JoinColumn(name = "identity_id"), inverseJoinColumns = @JoinColumn(name = "id"), inverseForeignKey = @ForeignKey(ConstraintMode.NO_CONSTRAINT))
@Fetch(FetchMode.JOIN)
@BatchSize(size = 50)
public Set<Identity> inChunk = new LinkedHashSet<>();
@Transient
public Set<ChunkLoader> loadedBy = new LinkedHashSet<>();
public Chunk() {}
public Chunk(int x, int y, Date createdOn) {
this.x = x;
this.y = y;
this.createdOn = createdOn;
}
}
@Entity
@Table(name = "location")
@Access(AccessType.FIELD)
public class Transform extends HibernateComponent {
@Embedded
public Vector2 position = new Vector2();
@ManyToOne
@JoinColumn(name = "chunk_id", referencedColumnName = "identity_id", updatable = false)
@Fetch(FetchMode.JOIN)
public Chunk chunk;
@Transient
public Vector2 previousPos = new Vector2();
public Transform() {}
public Transform(Vector2 position) { this.position = position; }
public Transform(Vector2 position, Chunk chunk) { this.position = position; this.chunk = chunk; }
}
The exception i get
19:29:05,126 INFO [ForkJoinPool.commonPool-worker-19] Extensions - {Game}: Update : java.util.ConcurrentModificationException:
::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
Exception: java.util.ConcurrentModificationException
Message: *** Null ***
+--- --- ---+
Stack Trace:
+--- --- ---+
java.base/java.util.HashMap$HashIterator.nextNode(HashMap.java:1493)
java.base/java.util.HashMap$KeyIterator.next(HashMap.java:1516)
org.hibernate.persister.collection.AbstractCollectionPersister.insertRows(AbstractCollectionPersister.java:1555)
org.hibernate.action.internal.CollectionUpdateAction.execute(CollectionUpdateAction.java:89)
org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:604)
org.hibernate.engine.spi.ActionQueue.lambda$executeActions$1(ActionQueue.java:478)
java.base/java.util.LinkedHashMap.forEach(LinkedHashMap.java:684)
org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:475)
org.hibernate.event.internal.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:348)
org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:40)
org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:102)
org.hibernate.internal.SessionImpl.doFlush(SessionImpl.java:1356)
org.hibernate.internal.SessionImpl.flush(SessionImpl.java:1343)
com.parallelorigin.persistence.database.ECSDatabase.lambda$updateEntities$16(ECSDatabase.java:242)
java.base/java.util.concurrent.CompletableFuture$AsyncRun.run(CompletableFuture.java:1736)
java.base/java.util.concurrent.CompletableFuture$AsyncRun.exec(CompletableFuture.java:1728)
java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:290)
java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1020)
java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1656)
java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1594)
java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:177)
::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
Anyone having an idea why hibernate throws that internal exception and what i could do to solve this issue ?
解决方案
You shouldn't change the list of entities, identities or components that you persist/update while another thread is working on it.
The thread that persists/updates entities must own the entity objects i.e. no other thread may interfere with the state while the transaction is running. You can only make use of the objects again after the transaction finished.
I don't know what your application does, but if you need access to the objects in your main thread you could copy the objects for the flush operation. This way, the thread doing the flush will properly own the objects and can safely work on them.
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