apache/hadoop · error · IOException

Only read ${actualNumPools} cache pools out of ${expectedNum

Error message

Only read ${actualNumPools} cache pools out of ${expectedNumPools}

What it means

Error "Only read ${actualNumPools} cache pools out of ${expectedNumPools}" thrown in apache/hadoop.

Source

Thrown at hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/offlineImageViewer/OfflineImageReconstructor.java:1100

      Integer expectedNumPools =
          node.removeChildInt(CACHE_MANAGER_SECTION_NUM_POOLS);
      if (expectedNumPools == null) {
        throw new IOException("CacheManager section had no <numPools>");
      }
      b.setNumPools(expectedNumPools);
      Integer expectedNumDirectives =
          node.removeChildInt(CACHE_MANAGER_SECTION_NUM_DIRECTIVES);
      if (expectedNumDirectives == null) {
        throw new IOException("CacheManager section had no <numDirectives>");
      }
      b.setNumDirectives(expectedNumDirectives);
      b.build().writeDelimitedTo(out);
      long actualNumPools = 0;
      while (actualNumPools < expectedNumPools) {
        try {
          expectTag(CACHE_MANAGER_SECTION_POOL, false);
        } catch (IOException e) {
          throw new IOException("Only read " + actualNumPools +
              " cache pools out of " + expectedNumPools, e);
        }
        actualNumPools++;
        Node pool = new Node();
        loadNodeChildren(pool, "pool fields", "");
        processPoolXml(node);
      }
      long actualNumDirectives = 0;
      while (actualNumDirectives < expectedNumDirectives) {
        try {
          expectTag(CACHE_MANAGER_SECTION_DIRECTIVE, false);
        } catch (IOException e) {
          throw new IOException("Only read " + actualNumDirectives +
              " cache pools out of " + expectedNumDirectives, e);
        }
        actualNumDirectives++;
        Node pool = new Node();
        loadNodeChildren(pool, "directive fields", "");

View on GitHub (pinned to 2add963021)

Solutions

1. The XML is truncated or its <numPools> count is wrong; correct the count or add the missing <pool> stanzas.
2. Regenerate the fsimage XML with 'hdfs oiv' from a valid fsimage.

When it happens

Trigger: Thrown by oiv -r when fewer cache pool stanzas are present than the count declared by <numPools>, indicating truncated or corrupt fsimage XML.

Common situations: See trigger scenarios.

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/f8db7cd6833065ea. Report an issue: GitHub.