apache/druid · error · IllegalStateException

Could not create user [%s] due to concurrent update contenti

Error message

Could not create user [%s] due to concurrent update contention.

What it means

Thrown as IllegalStateException when createUserInternal exhausts all retries while trying to create a user in the authorizer user map via compare-and-swap. Concurrent modifications of the shared user map prevented the update from committing within the retry budget. This can also surface during startup via initSuperUsersAndGroupMapping.

Source

Thrown at extensions-core/druid-basic-security/src/main/java/org/apache/druid/security/basic/authorization/db/updater/CoordinatorBasicAuthorizerMetadataStorageUpdater.java:669

  }

  private void createUserInternal(String prefix, String userName)
  {
    int attempts = 0;
    while (attempts < numRetries) {
      if (createUserOnce(prefix, userName)) {
        return;
      } else {
        attempts++;
      }
      try {
        Thread.sleep(ThreadLocalRandom.current().nextLong(UPDATE_RETRY_DELAY));
      }
      catch (InterruptedException ie) {
        throw new RuntimeException(ie);
      }
    }
    throw new ISE("Could not create user [%s] due to concurrent update contention.", userName);
  }

  private void deleteUserInternal(String prefix, String userName)
  {
    int attempts = 0;
    while (attempts < numRetries) {
      if (deleteUserOnce(prefix, userName)) {
        return;
      } else {
        attempts++;
      }
      try {
        Thread.sleep(ThreadLocalRandom.current().nextLong(UPDATE_RETRY_DELAY));
      }
      catch (InterruptedException ie) {
        throw new RuntimeException(ie);
      }
    }

View on GitHub (pinned to 9b90983fd2)

Solutions

Verify a single coordinator leader is performing authorizer updates
Reduce concurrent authorizer user-management traffic and retry the create
Check metadata store health and latency
Increase retry parameters or upgrade Druid if the contention pattern is known

Example fix

// before
client.createAuthorizerUser(authorizerName, userName); // ISE under contention
// after
try {
  client.createAuthorizerUser(authorizerName, userName);
} catch (IllegalStateException e) {
  backoffAndRetry(() -> client.createAuthorizerUser(authorizerName, userName));
}

Defensive patterns

Strategy: retry

Validate before calling

// check existence first to avoid CAS churn
Response r = client.getAuthorizerUser(authorizerName, userName);
if (r.getStatus() == 200) { /* already exists */ return; }

Try / catch

try {
  client.createAuthorizerUser(authorizerName, userName);
} catch (IllegalStateException e) {
  backoffAndRetry(() -> client.createAuthorizerUser(authorizerName, userName));
}

Prevention

Guarantee single-coordinator leadership for authorizer updates
Avoid parallel authorizer user creation from multiple tools
Watch metadata store health; slow stores increase CAS failure rates

When it happens

Trigger: Calling createUser on the authorizer storage updater (or cluster startup writing super-users) while other writers repeatedly change the same authorizer user map so every CAS fails.

Common situations: Multiple coordinators writing simultaneously (leadership ambiguity); concurrent admin/API user creation; slow or overloaded metadata store lengthening the contention window; init-time races when several nodes start with authorizer updates enabled.

Understand the failure class

Background: "This is a bug, please report it": internal invariant violations, unreachable panics, and SNH errors explained — this error's family across 47 libraries.

Related errors

AI-assisted analysis of apache/druid@9b90983fd2 (2026-09-07). Data as JSON: /api/errors/626e9babc2552044. Report an issue: GitHub.