序
本文主要研究下hikari连接池的validationTimeout
validationTimeout
默认是5秒
HikariCP/2.7.6/HikariCP-2.7.6-sources.jar!/com/zaxxer/hikari/pool/PoolBase.java
boolean isConnectionAlive(final Connection connection)
{
try {
try {
setNetworkTimeout(connection, validationTimeout);
final int validationSeconds = (int) Math.max(1000L, validationTimeout) / 1000;
if (isUseJdbc4Validation) {
return connection.isValid(validationSeconds);
}
try (Statement statement = connection.createStatement()) {
if (isNetworkTimeoutSupported != TRUE) {
setQueryTimeout(statement, validationSeconds);
}
statement.execute(config.getConnectionTestQuery());
}
}
finally {
setNetworkTimeout(connection, networkTimeout);
if (isIsolateInternalQueries && !isAutoCommit) {
connection.rollback();
}
}
return true;
}
catch (Exception e) {
lastConnectionFailure.set(e);
LOGGER.warn("{} - Failed to validate connection {} ({})", poolName, connection, e.getMessage());
return false;
}
}
/**
* Set the network timeout, if isUseNetworkTimeout is true and the
* driver supports it.
*
* @param connection the connection to set the network timeout on
* @param timeoutMs the number of milliseconds before timeout
* @throws SQLException throw if the connection.setNetworkTimeout() call throws
*/
private void setNetworkTimeout(final Connection connection, final long timeoutMs) throws SQLException
{
if (isNetworkTimeoutSupported == TRUE) {
connection.setNetworkTimeout(netTimeoutExecutor, (int) timeoutMs);
}
}
/**
* Set the query timeout, if it is supported by the driver.
*
* @param statement a statement to set the query timeout on
* @param timeoutSec the number of seconds before timeout
*/
private void setQueryTimeout(final Statement statement, final int timeoutSec)
{
if (isQueryTimeoutSupported != FALSE) {
try {
statement.setQueryTimeout(timeoutSec);
isQueryTimeoutSupported = TRUE;
}
catch (Throwable e) {
if (isQueryTimeoutSupported == UNINITIALIZED) {
isQueryTimeoutSupported = FALSE;
LOGGER.info("{} - Failed to set query timeout for statement. ({})", poolName, e.getMessage());
}
}
}
}如果是jdbc4的话，可以使用isUseJdbc4Validation，是直接利用connection.isValid(validationSeconds)来验证连接的有效性；否则的话则用connectionTestQuery查询语句来查询验证。this.isUseJdbc4Validation = config.getConnectionTestQuery() == null;当connectionTestQuery为null的时候，isUseJdbc4Validation为true
HikariPool.getConnection
HikariCP-2.7.6-sources.jar!/com/zaxxer/hikari/pool/HikariPool.java
/**
* Get a connection from the pool, or timeout after the specified number of milliseconds.
*
* @param hardTimeout the maximum time to wait for a connection from the pool
* @return a java.sql.Connection instance
* @throws SQLException thrown if a timeout occurs trying to obtain a connection
*/
public Connection getConnection(final long hardTimeout) throws SQLException
{
suspendResumeLock.acquire();
final long startTime = currentTime();
try {
long timeout = hardTimeout;
do {
PoolEntry poolEntry = connectionBag.borrow(timeout, MILLISECONDS);
if (poolEntry == null) {
break; // We timed out... break and throw exception
}
final long now = currentTime();
if (poolEntry.isMarkedEvicted() || (elapsedMillis(poolEntry.lastAccessed, now) > ALIVE_BYPASS_WINDOW_MS && !isConnectionAlive(poolEntry.connection))) {
closeConnection(poolEntry, poolEntry.isMarkedEvicted() ? EVICTED_CONNECTION_MESSAGE : DEAD_CONNECTION_MESSAGE);
timeout = hardTimeout - elapsedMillis(startTime);
}
else {
metricsTracker.recordBorrowStats(poolEntry, startTime);
return poolEntry.createProxyConnection(leakTaskFactory.schedule(poolEntry), now);
}
} while (timeout > 0L);
metricsTracker.recordBorrowTimeoutStats(startTime);
throw createTimeoutException(startTime);
}
catch (InterruptedException e) {
Thread.currentThread().interrupt();
throw new SQLException(poolName + " - Interrupted during connection acquisition", e);
}
finally {
suspendResumeLock.release();
}
}可以看到borrow到poolEntry之后，如果不是isMarkedEvicted，则会调用isConnectionAlive来判断连接的有效性
HikariPool
HikariCP-2.7.6-sources.jar!/com/zaxxer/hikari/pool/HikariPool.java
/**
* The house keeping task to retire and maintain minimum idle connections.
*/
private final class HouseKeeper implements Runnable
{
private volatile long previous = plusMillis(currentTime(), -HOUSEKEEPING_PERIOD_MS);
@Override
public void run()
{
try {
// refresh timeouts in case they changed via MBean
connectionTimeout = config.getConnectionTimeout();
validationTimeout = config.getValidationTimeout();
leakTaskFactory.updateLeakDetectionThreshold(config.getLeakDetectionThreshold());
final long idleTimeout = config.getIdleTimeout();
final long now = currentTime();
// Detect retrograde time, allowing +128ms as per NTP spec.
if (plusMillis(now, 128) < plusMillis(previous, HOUSEKEEPING_PERIOD_MS)) {
LOGGER.warn("{} - Retrograde clock change detected (housekeeper delta={}), soft-evicting connections from pool.",
poolName, elapsedDisplayString(previous, now));
previous = now;
softEvictConnections();
return;
}
else if (now > plusMillis(previous, (3 * HOUSEKEEPING_PERIOD_MS) / 2)) {
// No point evicting for forward clock motion, this merely accelerates connection retirement anyway
LOGGER.warn("{} - Thread starvation or clock leap detected (housekeeper delta={}).", poolName, elapsedDisplayString(previous, now));
}
previous = now;
String afterPrefix = "Pool ";
if (idleTimeout > 0L && config.getMinimumIdle() < config.getMaximumPoolSize()) {
logPoolState("Before cleanup ");
afterPrefix = "After cleanup ";
final List notInUse = connectionBag.values(STATE_NOT_IN_USE);
int toRemove = notInUse.size() - config.getMinimumIdle();
for (PoolEntry entry : notInUse) {
if (toRemove > 0 && elapsedMillis(entry.lastAccessed, now) > idleTimeout && connectionBag.reserve(entry)) {
closeConnection(entry, "(connection has passed idleTimeout)");
toRemove--;
}
}
}
logPoolState(afterPrefix);
fillPool(); // Try to maintain minimum connections
}
catch (Exception e) {
LOGGER.error("Unexpected exception in housekeeping task", e);
}
}
} HouseKeeper线程也用到了validationTimeout
小结
validationTimeout用来指定验证连接有效性的超时时间(默认是5秒，最小不能小于250毫秒)，如果是没有设置connectionTestQuery的话，默认是用jdbc4规范中的connection.isValid(validationSeconds)来验证连接的有效性。
另外hikari是在borrow连接的时候校验连接的有效性，相当于tomcat jdbc pool的testOnBorrow=true
doc
- configuration-knobs-baby