pip-325.md

Background knowledge

In the current implementation of Pulsar Transaction, Topics ensure that consumers do not read messages belonging to uncommitted transactions through the Transaction Buffer. Within the Transaction Buffer, a Position (maxReadPosition) is maintained, as well as a set of aborted transactions (aborts). The maxReadPosition controls the maximum message position that the broker can read, and it is adjusted to the position just before the first message of the first ongoing transaction when a transaction is committed or aborted. Before distributing messages to consumers, the broker filters out messages that belong to already aborted transactions using the aborts set.

Motivation

If we have a stuck transaction, then the transactions after this one cannot be consumed by the consumer even if they have been committed. The consumer will be stuck until the stuck transaction is aborted due to timeout, and then it will continue to consume messages. Therefore, we need to add a command to allow cluster administrators to proactively abort transaction.

Goals

In Scope

Introduce a new API for aborting transactions, allowing administrators to proactively abort transaction.

Out of Scope

None.

High Level Design

Introduce a new API for aborting transactions, allowing administrators to proactively abort transaction.

Detailed Design

Design & Implementation Details

Introduce a new API for aborting transactions, allowing administrators to proactively abort transaction.

Public-facing Changes

Public API

Add a new API to abort transaction:

    /**
     * Abort a transaction.
     *
     * @param txnID the txnId
     */
    void abortTransaction(TxnID txnID) throws PulsarAdminException;

    /**
     * Asynchronously Abort a transaction.
     *
     * @param txnID the txnId
     */
    CompletableFuture<Void> abortTransactionAsync(TxnID txnID);

admin.transactions().abortTransaction(txnID);

Binary protocol

Configuration

CLI

Add a command to abort transaction:

pulsar-admin transactions abort-transaction --most-sig-bits 1 --least-sig-bits 2

Metrics

None.

Monitoring

None.

Security Considerations

The transaction owner and super user can access the admin API to abort the transaction.

Backward & Forward Compatibility

Revert

Upgrade

Alternatives

General Notes

Links

• Mailing List discussion thread: https://lists.apache.org/thread/ssgngyrlgx36zvygvsd5b2dm5q6krn0f
• Mailing List voting thread: https://lists.apache.org/thread/kp9w4d8drngomx1mdof0203ybgfmvtty