apache/hadoop · error · ClosedIOException

KeepAliveCache is closed

Error message

KeepAliveCache is closed

What it means

Error "KeepAliveCache is closed" thrown in apache/hadoop.

Source

Thrown at hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azurebfs/services/KeepAliveCache.java:208

    while (size() != 0) {
      closeHttpClientConnection(pollFirst());
    }
  }

  /**
   * Gets the oldest added HttpClientConnection from the cache. The returned connection
   * is open.
   * The cache follows the FIFO strategy. If the connection is not open, it will
   * be closed and the next connection is checked. Once a valid connection is found,
   * it is returned.
   * @return HttpClientConnection: if a valid connection is found, else null.
   * @throws IOException if the cache is closed.
   */
  public HttpClientConnection get() throws IOException {
    if (getIsClosed()) {
      LOG.debug("Attempt to get connection from closed cache for account: {}",
          accountNamePath);
      throw new ClosedIOException(accountNamePath, KEEP_ALIVE_CACHE_CLOSED);
    }
    HttpClientConnection httpClientConnection;
    while ((httpClientConnection = pollFirst()) != null) {
      if (!httpClientConnection.isOpen() || httpClientConnection.isStale()) {
        closeHttpClientConnection(httpClientConnection);
        continue;
      }
      return httpClientConnection;
    }
    LOG.debug("No valid connection found in cache for account: {}",
        accountNamePath);
    return null;
  }

  /**
   * Puts the HttpClientConnection in the cache. If the size of cache is equal to
   * maxConn, the oldest connection is closed and removed from the cache, which
   * will make space for the new connection. If the cache is closed or of zero size,

View on GitHub (pinned to 2add963021)

Solutions

1. Do not use the HTTP connection keep-alive cache after the filesystem/client is closed.
2. Open a new filesystem instance for further operations.

When it happens

Trigger: Code attempts to reuse the keep-alive cache after the ABFS client shut it down.

Common situations: See trigger scenarios.

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/d92a94cd01aebc62. Report an issue: GitHub.