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将Spring用于高并发环境的隐忧2008-04-22 来自：villa123  [收藏到我的网摘]

最近协助一些BEA客户做调优，他们使用了Spring，出现了各种各样的性能问题，这些问题其实都是不容易重现的，其中，我自己捕获了一些ThreadDump，并report了给Spring JIRA。这个Case的情况是：Spring会偶然出现CPU 100%的情况，WebLogic Server崩溃，我后来分析了线程Dump，觉得是一种Lock Contention的情形，幸好，Juergen Hoeller很快给我Fixed了这个Bug：
http://jira.springframework.org/browse/SPR-4664

使用Java编程的同学都建议Review一下，呵呵：

这是2.5.4以前的代码：

/**
* Cache of TransactionAttributes, keyed by DefaultCacheKey (Method + target Class).
*

As this base class is not marked Serializable, the cache will be recreated
* after serialization - provided that the concrete subclass is Serializable.
*/
final Map attributeCache = new HashMap();

/**
* Determine the transaction attribute for this method invocation.
*

Defaults to the class's transaction attribute if no method attribute is found.
* @param method the method for the current invocation (never null)
* @param targetClass the target class for this invocation (may be null)
* @return TransactionAttribute for this method, or null if the method
* is not transactional
*/
public TransactionAttribute getTransactionAttribute(Method method, Class targetClass) {
// First, see if we have a cached value.
Object cacheKey = getCacheKey(method, targetClass);
synchronized ( this .attributeCache) {
Object cached = this .attributeCache.get(cacheKey);
if (cached != null ) {
// Value will either be canonical value indicating there is no transaction attribute,
// or an actual transaction attribute.
if (cached == NULL_TRANSACTION_ATTRIBUTE) {
return null ;
}
else {
return (TransactionAttribute) cached;
}
}
else {
// We need to work it out.
TransactionAttribute txAtt = computeTransactionAttribute(method, targetClass);
// Put it in the cache.
if (txAtt == null ) {
this .attributeCache.put(cacheKey, NULL_TRANSACTION_ATTRIBUTE);
}
else {
if (logger.isDebugEnabled()) {
logger.debug( " Adding transactional method [ " + method.getName() + " ] with attribute [ " + txAtt + " ] " );
}
this .attributeCache.put(cacheKey, txAtt);
}
return txAtt;
}
}
}

这是2.5.4 Fixed后的代码：


/**
* Cache of TransactionAttributes, keyed by DefaultCacheKey (Method + target Class).
*

As this base class is not marked Serializable, the cache will be recreated
* after serialization - provided that the concrete subclass is Serializable.
*/
final Map attributeCache = CollectionFactory.createConcurrentMapIfPossible( 16 );


/**
* Determine the transaction attribute for this method invocation.
*

Defaults to the class's transaction attribute if no method attribute is found.
* @param method the method for the current invocation (never null)
* @param targetClass the target class for this invocation (may be null)
* @return TransactionAttribute for this method, or null if the method
* is not transactional
*/
public TransactionAttribute getTransactionAttribute(Method method, Class targetClass) {
// First, see if we have a cached value.
Object cacheKey = getCacheKey(method, targetClass);
Object cached = this .attributeCache.get(cacheKey);
if (cached != null ) {
// Value will either be canonical value indicating there is no transaction attribute,
// or an actual transaction attribute.
if (cached == NULL_TRANSACTION_ATTRIBUTE) {
return null ;
}
else {
return (TransactionAttribute) cached;
}
}
else {
// We need to work it out.
TransactionAttribute txAtt = computeTransactionAttribute(method, targetClass);
// Put it in the cache.
if (txAtt == null ) {
this .attributeCache.put(cacheKey, NULL_TRANSACTION_ATTRIBUTE);
}
else {
if (logger.isDebugEnabled()) {
logger.debug( " Adding transactional method [ " + method.getName() + " ] with attribute [ " + txAtt + " ] " );
}
this .attributeCache.put(cacheKey, txAtt);
}
return txAtt;
}
}

但是2.5.4 snapshot是未经很好测试的版本，客户一般不太敢用。
我不知道其实有多少客户真正地把Spring投入到高并发性环境下使用，
如果有，他们应该会能碰到我所碰到的情形。

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