@@ -114,8 +114,9 @@ public abstract class ClientPool<C, E extends Exception> implements Closeable {
           if (!clients.isEmpty()) {
             return clients.removeFirst();
           } else if (currentSize < poolSize) {
+            C client = newClient();
             currentSize += 1;
-            return newClient();
+            return client;
           }
         }
       }
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 * to you under the Apache License, Version 2.0 (the
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package org.apache.iceberg.hive;

import java.io.Closeable;
import java.util.ArrayDeque;
import java.util.Deque;
import org.apache.iceberg.relocated.com.google.common.base.Preconditions;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public abstract class ClientPool<C, E extends Exception> implements Closeable {
  private static final Logger LOG = LoggerFactory.getLogger(ClientPool.class);

  private final int poolSize;
  private final Deque<C> clients;
  private final Class<? extends E> reconnectExc;
  private final Object signal = new Object();
  private volatile int currentSize;
  private boolean closed;

  ClientPool(int poolSize, Class<? extends E> reconnectExc) {
    this.poolSize = poolSize;
    this.reconnectExc = reconnectExc;
    this.clients = new ArrayDeque<>(poolSize);
    this.currentSize = 0;
    this.closed = false;
  }

  public interface Action<R, C, E extends Exception> {
    R run(C client) throws E;
  }

  public <R> R run(Action<R, C, E> action) throws E, InterruptedException {
    C client = get();
    try {
      return action.run(client);

    } catch (Exception exc) {
      if (reconnectExc.isInstance(exc)) {
        try {
          client = reconnect(client);
        } catch (Exception ignored) {
          // if reconnection throws any exception, rethrow the original failure
          throw reconnectExc.cast(exc);
        }

        return action.run(client);
      }

      throw exc;

    } finally {
      release(client);
    }
  }

  protected abstract C newClient();

  protected abstract C reconnect(C client);

  protected abstract void close(C client);

  @Override
  public void close() {
    this.closed = true;
    try {
      while (currentSize > 0) {
        if (!clients.isEmpty()) {
          synchronized (this) {
            if (!clients.isEmpty()) {
              C client = clients.removeFirst();
              close(client);
              currentSize -= 1;
            }
          }
        }
        if (clients.isEmpty() && currentSize > 0) {
          // wake every second in case this missed the signal
          synchronized (signal) {
            signal.wait(1000);
          }
        }
      }

    } catch (InterruptedException e) {
      Thread.currentThread().interrupt();
      LOG.warn("Interrupted while shutting down pool. Some clients may not be closed.", e);
    }
  }

  private C get() throws InterruptedException {
    Preconditions.checkState(!closed, "Cannot get a client from a closed pool");
    while (true) {
      if (!clients.isEmpty() || currentSize < poolSize) {
        synchronized (this) {
          if (!clients.isEmpty()) {
            return clients.removeFirst();
          } else if (currentSize < poolSize) {
            currentSize += 1;
            return newClient();
          }
        }
      }
      synchronized (signal) {
        // wake every second in case this missed the signal
        signal.wait(1000);
      }
    }
  }

  private void release(C client) {
    synchronized (this) {
      clients.addFirst(client);
    }
    synchronized (signal) {
      signal.notify();
    }
  }
}

This is real issue here right? We have the possibility of incrementing current size even if "newClient" failed in the old code? If so this seems like the right fix to me