REDIS (13) 并发使用Jedis原理分析
1. jedis的部分源码 了解connectTimeout和socketTimeOut参数
我们先从Jedis的源代码入手了解Jedis
JedisPool pool = new JedisPool(poolConfig, host, port, timeout, psw, database);找到JedisFactory.makeObject()。上面的timeout参数传给了下面connectionTimeOut和soTimeOut，最终这两个参数传给了JSE的Socket类的实例。
@Override
public PooledObject makeObject() throws Exception {
final HostAndPort hostAndPort = this.hostAndPort.get();
final Jedis jedis = new Jedis(hostAndPort.getHost(), hostAndPort.getPort(), connectionTimeout,
soTimeout);
jedis.connect();
if (null != this.password) {
jedis.auth(this.password);
}
if (database != 0) {
jedis.select(database);
}
if (clientName != null) {
jedis.clientSetname(clientName);
}
return new DefaultPooledObject(jedis);
} 最后我们找到
public void connect() {
if (!isConnected()) {
try {
socket = new Socket();
// ->@wjw_add
socket.setReuseAddress(true);
socket.setKeepAlive(true); // Will monitor the TCP connection is
// valid
socket.setTcpNoDelay(true); // Socket buffer Whetherclosed, to
// ensure timely delivery of data
socket.setSoLinger(true, 0); // Control calls close () method,
// the underlying socket is closed
// immediately
// <-@wjw_add
socket.connect(new InetSocketAddress(host, port), connectionTimeout);
socket.setSoTimeout(soTimeout);
outputStream = new RedisOutputStream(socket.getOutputStream());
inputStream = new RedisInputStream(socket.getInputStream());
} catch (IOException ex) {
broken = true;
throw new JedisConnectionException(ex);
}
}
}2.并发测试: Jedis线程不安全
JedisPool pool = new JedisPool(poolConfig, "123.56.XX.XX", 6379, 0, "foobared", 13);
AtomicInteger n =new AtomicInteger(1000);
String timeStr = TimeTool.formatTime(System.currentTimeMillis(), "yyyy_MM_dd_HH_mm_ss_SSS");
ThreadTool.sleep(100);
try (Jedis jedis = pool.getResource()) {
while(n.decrementAndGet()>0){
new Thread(()->{
System.out.print(".");
Long rst = jedis.incr(timeStr);
LogCore.BASE.info("test={}", rst);
}).start();
}
} catch (Exception e) {
LogCore.BASE.info("manager fatal err,", e);
}
报的异常:
Exception in thread "Thread-925" redis.clients.jedis.exceptions.JedisConnectionException: java.net.SocketException: Broken pipe (Write failed)
at redis.clients.jedis.Protocol.sendCommand(Protocol.java:98)
at redis.clients.jedis.Protocol.sendCommand(Protocol.java:78)
at redis.clients.jedis.Connection.sendCommand(Connection.java:101)
at redis.clients.jedis.BinaryClient.incr(BinaryClient.java:217)
at redis.clients.jedis.Client.incr(Client.java:135)
at redis.clients.jedis.Jedis.incr(Jedis.java:538)
at com.sincetimes.website.redis.jedis.excample.ConcurrentTest.lambda$0(ConcurrentTest.java:34)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.net.SocketException: Broken pipe (Write failed)
at java.net.SocketOutputStream.socketWrite0(Native Method)
at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:111)
at java.net.SocketOutputStream.write(SocketOutputStream.java:155)
at redis.clients.util.RedisOutputStream.flushBuffer(RedisOutputStream.java:31)
at redis.clients.util.RedisOutputStream.write(RedisOutputStream.java:38)
at redis.clients.jedis.Protocol.sendCommand(Protocol.java:84)
... 7 more
Exception in thread "Thread-924" redis.clients.jedis.exceptions.JedisConnectionException: java.net.SocketException: Broken pipe (Write failed)
at redis.clients.jedis.Protocol.sendCommand(Protocol.java:98)
at redis.clients.jedis.Protocol.sendCommand(Protocol.java:78)
at redis.clients.jedis.Connection.sendCommand(Connection.java:101)
at redis.clients.jedis.BinaryClient.incr(BinaryClient.java:217)
at redis.clients.jedis.Client.incr(Client.java:135)
at redis.clients.jedis.Jedis.incr(Jedis.java:538)
at com.sincetimes.website.redis.jedis.excample.ConcurrentTest.lambda$0(ConcurrentTest.java:34)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.net.SocketException: Broken pipe (Write failed)
at java.net.SocketOutputStream.socketWrite0(Native Method)
at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:111)
at java.net.SocketOutputStream.write(SocketOutputStream.java:155)
at redis.clients.util.RedisOutputStream.flushBuffer(RedisOutputStream.java:31)
at redis.clients.util.RedisOutputStream.write(RedisOutputStream.java:38)
at redis.clients.jedis.Protocol.sendCommand(Protocol.java:84)
... 7 more3.并发测试 JedisPool是线程安全的 了解maxTotal和maxWaitMillis参数
JedisPool pool = new JedisPool(poolConfig, "123.56.XX.XX", 6379, 0, "foobared", 13);
AtomicInteger n =new AtomicInteger(1000);
ThreadTool.sleep(100);
while(n.decrementAndGet()>0){
new Thread(()->{
try (Jedis jedis = pool.getResource()) {
LogCore.BASE.info("test={}", jedis.set("test", "n"+n.get()));
} catch (Exception e) {
LogCore.BASE.info("manager fatal err,", e);
}
}).start();
}
pool.close();4.JedisPool的实现
4.1 从连接池获取Jedis
T org.apache.commons.pool2.impl.GenericObjectPool.borrowObject(long borrowMaxWaitMillis)
public T borrowObject(long borrowMaxWaitMillis) throws Exception {
assertOpen();
AbandonedConfig ac = this.abandonedConfig;
if (ac != null && ac.getRemoveAbandonedOnBorrow() &&
(getNumIdle() < 2) &&
(getNumActive() > getMaxTotal() - 3) ) {
removeAbandoned(ac);
}
PooledObject p = null;
// Get local copy of current config so it is consistent for entire
// method execution
boolean blockWhenExhausted = getBlockWhenExhausted();
boolean create;
long waitTime = System.currentTimeMillis();
while (p == null) {
create = false;
if (blockWhenExhausted) {
p = idleObjects.pollFirst();
if (p == null) {
p = create();
if (p != null) {
create = true;
}
}
if (p == null) {
if (borrowMaxWaitMillis < 0) {
p = idleObjects.takeFirst();
} else {
p = idleObjects.pollFirst(borrowMaxWaitMillis,
TimeUnit.MILLISECONDS);
}
}
if (p == null) {
throw new NoSuchElementException(
"Timeout waiting for idle object");
}
if (!p.allocate()) {
p = null;
}
} else {
p = idleObjects.pollFirst();
if (p == null) {
p = create();
if (p != null) {
create = true;
}
}
if (p == null) {
throw new NoSuchElementException("Pool exhausted");
}
if (!p.allocate()) {
p = null;
}
}
if (p != null) {
try {
factory.activateObject(p);
} catch (Exception e) {
try {
destroy(p);
} catch (Exception e1) {
// Ignore - activation failure is more important
}
p = null;
if (create) {
NoSuchElementException nsee = new NoSuchElementException(
"Unable to activate object");
nsee.initCause(e);
throw nsee;
}
}
if (p != null && (getTestOnBorrow() || create && getTestOnCreate())) {
boolean validate = false;
Throwable validationThrowable = null;
try {
validate = factory.validateObject(p);
} catch (Throwable t) {
PoolUtils.checkRethrow(t);
validationThrowable = t;
}
if (!validate) {
try {
destroy(p);
destroyedByBorrowValidationCount.incrementAndGet();
} catch (Exception e) {
// Ignore - validation failure is more important
}
p = null;
if (create) {
NoSuchElementException nsee = new NoSuchElementException(
"Unable to validate object");
nsee.initCause(validationThrowable);
throw nsee;
}
}
}
}
}
updateStatsBorrow(p, System.currentTimeMillis() - waitTime);
return p.getObject();
} 其中borrowMaxWaitMillis的就是maxWaitMillis默认值为-1
也就是上面的一大堆我们只需要关心如下的代码：
if (borrowMaxWaitMillis < 0) {
p = idleObjects.takeFirst();
} else {
p = idleObjects.pollFirst(borrowMaxWaitMillis,
TimeUnit.MILLISECONDS);
}
if (p == null) {
throw new NoSuchElementException("Timeout waiting for idle object");
}idleObjects是个阻塞队列,而且是双向的也就是Deque而不是Queue
(org.apache.commons.pool2.impl.LinkedBlockingDeque
这个类是apache的与Java的并发包下的LinkedBlockingDeque类似
至于为什么使用deque因为Apache的这套连接池是可以控制队列是先进先出FIFO还是先进后出LIFO的,JedisPoolConfig可以用.setLifo(lifo);来控制。
| apache.commons.pool2.impl.LinkedBlockingDeque | java.util.concurrent.LinkedBlockingDeque |
|---|---|
E takeFirst() throws InterruptedException |
E takeFirst() throws InterruptedException |
E pollFirst(long timeout, TimeUnit unit) |
E pollFirst(long timeout, TimeUnit unit) |
接口一样我们再比较下源码
jse:
public E takeFirst() throws InterruptedException {
final ReentrantLock lock = this.lock;
lock.lock();
try {
E x;
while ( (x = unlinkFirst()) == null)
notEmpty.await();
return x;
} finally {
lock.unlock();
}
}
public E pollFirst(long timeout, TimeUnit unit)
throws InterruptedException {
long nanos = unit.toNanos(timeout);
final ReentrantLock lock = this.lock;
lock.lockInterruptibly();
try {
E x;
while ( (x = unlinkFirst()) == null) {
if (nanos <= 0)
return null;
nanos = notEmpty.awaitNanos(nanos);
}
return x;
} finally {
lock.unlock();
}
}apache
public E takeFirst() throws InterruptedException {
lock.lock();
try {
E x;
while ( (x = unlinkFirst()) == null) {
notEmpty.await();
}
return x;
} finally {
lock.unlock();
}
}
public E pollFirst(long timeout, TimeUnit unit)
throws InterruptedException {
long nanos = unit.toNanos(timeout);
lock.lockInterruptibly();
try {
E x;
while ( (x = unlinkFirst()) == null) {
if (nanos <= 0) {
return null;
}
nanos = notEmpty.awaitNanos(nanos);
}
return x;
} finally {
lock.unlock();
}
}几乎一样
也就是当jedis从队列获取不到的时候，会阻塞直到队列非空。如果我们设置了maxWaitMillis参数，而jedispool已满(达到maxTotal)pool.getResouce在这个时间迟迟等不到其他的Jedis返回给连接池时就会报如下异常：
Caused by: java.util.NoSuchElementException: Timeout waiting for idle object
at org.apache.commons.pool2.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:449)
at redis.clients.util.Pool.getResource(Pool.java:48)
... 3 common frames omitted4.2 创建Jedis
可见localMaxTotal参数控制了最多生成的连接数
private PooledObject create() throws Exception {
int localMaxTotal = getMaxTotal();
long newCreateCount = createCount.incrementAndGet();
if (localMaxTotal > -1 && newCreateCount > localMaxTotal ||
newCreateCount > Integer.MAX_VALUE) {
createCount.decrementAndGet();
return null;
}
final PooledObject p;
try {
p = factory.makeObject();
} catch (Exception e) {
createCount.decrementAndGet();
throw e;
}
AbandonedConfig ac = this.abandonedConfig;
if (ac != null && ac.getLogAbandoned()) {
p.setLogAbandoned(true);
}
createdCount.incrementAndGet();
allObjects.put(new IdentityWrapper(p.getObject()), p);
return p;
} 总之，Jedis线程不安全，JedisPool线程安全。其最大的连接数和获取等待时间是可以设置上限的，用完后连接变为空闲，活跃的连接(active)和空闲的(idel)不会超过最大连接数(total)