Apache Http Client prints “[read] I/O error: Read timed out”"

Question

I am using apache http client v4.5 and using it as a REST client. In some cases I recognize an error \"[read] I/O error: Read timed out\" which comes from the httpclient fra

Answer 1

The reason is not "multithread", but "http client Pool".

It is not a error, just test the socket stale, and it is good when you want to reuse a socket. See org/apache/httpcomponents/httpcore/4.4.10/httpcore-4.4.10-sources.jar!/org/apache/http/pool/AbstractConnPool.java

for (;;) {
    final E leasedEntry = getPoolEntryBlocking(route, state, timeout, tunit, this);
    if (validateAfterInactivity > 0)  {
        if (leasedEntry.getUpdated() + validateAfterInactivity <= System.currentTimeMillis()) {
            if (!validate(leasedEntry)) {
                leasedEntry.close();
                release(leasedEntry, false);
                continue;
            }
        }
    }
    entryRef.set(leasedEntry);
    done.set(true);
    onLease(leasedEntry);
    if (callback != null) {
        callback.completed(leasedEntry);
    }
    return leasedEntry;
}

protected boolean validate(final CPoolEntry entry) {
    return !entry.getConnection().isStale();
}

public boolean isStale() {
    if (!isOpen()) {
        return true;
    }
    try {
        final int bytesRead = fillInputBuffer(1);
        return bytesRead < 0;
    } catch (final SocketTimeoutException ex) {
        return false;
    } catch (final IOException ex) {
        return true;
    }
}

org/apache/httpcomponents/httpcore/4.4.10/httpcore-4.4.10-sources.jar!/org/apache/http/impl/BHttpConnectionBase.java

private int fillInputBuffer(final int timeout) throws IOException {
final Socket socket = this.socketHolder.get();
final int oldtimeout = socket.getSoTimeout();
try {
    socket.setSoTimeout(timeout);
    return this.inbuffer.fillBuffer();
} finally {
    socket.setSoTimeout(oldtimeout);
}
}

Set socket timeout to 1 ms, and read input stream, return these results:

1. -1 recreate new connection
2. ">0" reuse connection
3. timeout exception, reuse connection
4. IO exception recreate new connection

To avoid this message, just set proper value for validateAfterInactivity , it's the min value of client socket timeout, keep-alive time(return by ConnectionKeepAliveStrategy), server connection timeout, and the delay time for idleConnectionMonitor. This does not check connection state, if connect is reset, a new connection will be created.