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我将服务器添加到 xmemcached 并尝试设置一些项目。我得到了这个例外

bar
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: -1
at java.util.ArrayList.elementData(ArrayList.java:371)
at java.util.ArrayList.get(ArrayList.java:384)
at net.rubyeye.xmemcached.impl.ArrayMemcachedSessionLocator.getSessionByKey(ArrayMemcachedSessionLocator.java:67)
at net.rubyeye.xmemcached.impl.MemcachedConnector.findSessionByKey(MemcachedConnector.java:570)
at net.rubyeye.xmemcached.impl.MemcachedConnector.send(MemcachedConnector.java:487)
at net.rubyeye.xmemcached.XMemcachedClient.sendCommand(XMemcachedClient.java:288)
at net.rubyeye.xmemcached.XMemcachedClient.fetch0(XMemcachedClient.java:617)
at net.rubyeye.xmemcached.XMemcachedClient.get0(XMemcachedClient.java:1030)
at net.rubyeye.xmemcached.XMemcachedClient.get(XMemcachedClient.java:988)
at net.rubyeye.xmemcached.XMemcachedClient.get(XMemcachedClient.java:999)
at net.rubyeye.xmemcached.XMemcachedClient.get(XMemcachedClient.java:1021)
at AxCacheEngine.Libs.AxMemcached.main(AxMemcached.java:33)

这是代码：

MemcachedClientBuilder builder = new XMemcachedClientBuilder(AddrUtil.getAddresses(
            "127.0.0.1:11211 127.0.0.1:11311"
    ));
builder.setSessionLocator(new ArrayMemcachedSessionLocator(HashAlgorithm.ONE_AT_A_TIME));

MemcachedClient memcachedClient = builder.build();
System.out.println("Trying to get 1 milllion items");

int hugeItems = 0;
int normalItems = 0;
int totalCount = 0;

System.out.println(memcachedClient.set("foo",0,"bar"));
System.out.println(memcachedClient.set("bar",0,"baz"));
System.out.println(memcachedClient.set("yin",0,"yang"));

可能是什么问题呢？分销策略有问题吗？当我尝试从 php-memcached 获取项目集时出现此错误。请帮忙

4

1 回答 1

0

我复制了您的问题，我认为您不能ArrayMemcachedSessionAllocator将One at a Time散列算法与 2 个或更多会话一起使用。

根据文档，ArrayMemcachedSessionAllocator该类将 Sessions 定位为hash(key) mod sessions.size().

这个数字将是代码中 Arraylist 的索引。特别是，这是有罪的行：

long start = this.getHash(size, key); //gets computed by ONE_AT_A_TIME hash % number of sessions
List<Session> sessions = sessionList.get((int) start); //this is where you get out of bounds

问题是这ONE_AT_A_TIME hash可能是负面的。它对bar（问题的根源）是负面的。

因此，如果您有一个负哈希值模 2（服务器数量），start也是一个负值。

另一方面，foo具有正哈希值One_At_a_Time并且模 2 仍然是正值！

注意：如果您有一台服务器，该算法工作得非常好（因为任何数字 % 1 都是正数）。

因此，我认为您不能将这种散列算法与ArrayMemcachedSessionAllocator2 个或更多服务器的类一起使用。

于 2013-12-08T21:30:05.940 回答