private static PoolDOMBuilder acquireDOMBuilder() throws TikaException {

        PoolDOMBuilder builder = null;
        DOM_POOL_LOCK
                .readLock()
                .lock();
        try {
            builder = DOM_BUILDERS.poll();
        } finally {
            DOM_POOL_LOCK
                    .readLock()
                    .unlock();
        }
        if (builder == null) {
            LOG.warn("Contention waiting for a DOMBuilder. " +
                    "Consider increasing the XMLReaderUtils.POOL_SIZE");

        }
        return builder;
    }
Acquire a DOMBuilder from the pool.  Make sure to
{@link #releaseDOMBuilder(PoolDOMBuilder)} in
a <code>finally</code> block every time you call this.

@return a DocumentBuilder or null if no DOMBuilders are available
@throws TikaException
tika-core/src/main/java/org/apache/tika/utils/XMLReaderUtils.java