neoppod 1.5.1

In zope

1. Edit your zope.conf, add a neo import and edit the zodb_db section by replacing its filestorage subsection by a NEOStorage one. It should look like:

   %import neo.client
   <zodb_db main>
       <NEOStorage>
           master_nodes 127.0.0.1:10000
           name <cluster name>
       </NEOStorage>
       mount-point /
   </zodb_db>

2. Start zope

In a Python script

Just create the storage object and play with it:

from neo.client.Storage import Storage
s = Storage(master_nodes="127.0.0.1:10010", name="main")
...

“name” and “master_nodes” parameters have the same meaning as in configuration file.

Shutting down

Before shutting down NEO, all clients like Zope instances should be stopped, so that cluster become idle. This is required for multi-DB setups, to prevent critical failures in second phase of TPC.

A cluster (i.e. masters+storages+admin) can be stopped gracefully by putting it in STOPPING state using neoctl:

neoctl -a <admin> set cluster STOPPING

This can also be done manually, which helps if your cluster is in bad state:

• Stop all master nodes first with a SIGINT or SIGTERM, so that storage nodes

  don’t become in OUT_OF_DATE state.

• Next stop remaining nodes with a SIGINT or SIGTERM.

Master-slave asynchronous replication

This is the recommanded way to backup a NEO cluster. Once a cluster with appropriate upstream_cluster & upstream_masters configuration is started, you can switch it into backup mode using:

neoctl -a <admin> set cluster STARTING_BACKUP

It remembers it is in such mode when it is stopped, and it can be put back into normal mode (RUNNING) by setting it into STOPPING_BACKUP state.

Packs are currently not replicated, which means packing should always be done up to a TID that is already fully replicated, so that the backup cluster has a full history (and not random holes).

SSL support

In addition to any external solution like OpenVPN, NEO has builtin SSL support to authenticate and encrypt communications between nodes.

All commands and configuration files have options to specify a CA certificate, the node certificate and the node private key. A certificate can be shared by several nodes.

NEO always uses the latest SSL protocol supported by the Python interpreter, without fallback to older versions. A “SSL: WRONG_VERSION_NUMBER” error means that a node runs in an older environment (Python + OpenSSL) than others.

Note also that you can’t mix non-SSL nodes and SSL nodes, even between a upstream cluster and a backup one. In doing so, connections can get stuck, or fail with malformed packets or SSL handshake errors.

1.5.1 (2015-10-26)

Several bugs and performance issues have been fixed in this release, mainly in the storage node.

• Importer storage backend:

  • Fix retrieval of an object from ZODB when next serial in NEO.

  • Fix crash of storage nodes when a transaction is aborted.

  • Faster resumption when many transactions have already been imported to MySQL.

• MySQL storage backend:

  • Refuse to start if max_allowed_packet is too small.

  • Faster commit of transaction metadata.

• Replication & checking of replicas:

  • Fix crash when a corruption is found while checking TIDs. 2 other issues remain unfixed: see BUGS file.

  • Speed up checking of replicas, at the cost of storage nodes being less responsive to other events.

• The master wrongly sent invalidations for objects on which only readCurrent was called, which caused invalid entries in client caches, or assertion failures in Connection._setstate_noncurrent.

1.5 (2015-10-05)

In this version, the connectivity between nodes has been greatly improved:

• Added SSL support.

• IPv4 & IPv6 can be mixed: some nodes can have an IPv4 binding address, whereas other listen on IPv6.

• Version 1.4 fixed several cases where nodes could reconnect too quickly, using 100% CPU and flooding logs. This is now fixed completely, for example when a backup storage node was rejected because the upstream cluster was not ready.

• Tickless poll loop, for lower latency and CPU usage: nodes don’t wake up every second anymore to check if a timeout has expired.

• Connections could be wrongly processed before being polled (for reading or writing). This happened if a file descriptor number was reallocated by the kernel for a connection, just after a connection was closed.

Other changes are:

• IStorage: history() did not wait the oid to be unlocked. This means that the latest version of an object could be missing from the result.

• Log files can now be specified in configuration files.

• ~(user) construction are expanded for all paths in configuration (file or command line). This does not concern non-daemon executables like neoctl.

• For neoctl, -l option now logs everything on disk automatically.

• The admin node do not reset anymore the list of known masters from configuration when reconnecting, for consistency with client nodes.

• Code refactoring and improvements to logging and debugging.

• An notable change in the test suite is that the occasional deadlocks that affected threaded tests have been fixed.

1.4 (2015-07-13)

This version comes with a change in the SQL tables format, to fix a potential crash of storage nodes when storing values that only differ by the compression flag. See UPGRADE notes if you think your application may be affected by this bug.

• Performance and features:

  • ‘Importer’ storage backend has been significantly sped up.

  • Support for TokuDB has been added to MySQL storage backend. The engine is still InnoDB by default, and it can be selected via a new ‘neostorage’ option.

  • A ‘neomaster’ option has been added to automatically start a new cluster if the number of pending storage nodes is greater than or equal to the specified value.

• Bugfixes:

  • Storage crashed when reading empty transactions. We still need to decide whether NEO should:

    • continue to store such transactions;

    • ignore them on commit, like other ZODB implementation;

    • or fail on commit.

  • Storage crashed when a client tries to “steal” the UUID of another client.

  • Client could get stuck forever on unreadable cells when not connected to the master.

  • Client could only instantiate NEOStorage from the main thread, and the RTMIN+2 signal displayed logs for only 1 NEOStorage. Now, RTMIN+2 & RTMIN+3 are setup when neo.client module is imported.

• Plus fixes and improvements to logging and debugging.

1.3 (2015-01-13)

• Version 1.2 added a new ‘Importer’ storage backend but it had 2 bugs.

  • An interrupted migration could not be resumed.

  • Merging several ZODB only worked if NEO could import all classes used by the application. This has been fixed by repickling without loading any object.

• Logging has been improved for a better integration with the environment:

  • RTMIN+1 signal was changed to reopen logs. RTMIN+1 & RTMIN+2 signals, which were previously used for debugging, have been remapped to RTMIN+2 & RTMIN+3

  • In Zope, client registers automatically for log rotation (USR2).

  • NEO logs are SQLite DB that are not open anymore with a persistent journal, because this is incompatible with the rename+reopen way to rotate logs, and we want to support logrotate.

  • ‘neolog’ can now open gzip/bz2 compressed logs transparently.

  • ‘neolog’ does not spam the console anymore when piped to a process that exits prematurely.

• MySQL backend has been updated to work with recent MariaDB (>=10).

• 2 ‘neomaster’ command-line options were added to set upstream cluster/masters.

1.2 (2014-07-30)

The most important changes in this version are the work about conversion of databases from/to NEO:

• A new ‘Importer’ storage backend has been implemented and this is now the recommended way to migrate existing Zope databases. See ‘importer.conf’ example file for more information.

• ‘neomigrate’ command refused to run since version 1.0

• Exported data serials by NEO iterator were wrong. There are still differences with FileStorage:

  • NEO always resolves to original serial, to avoid any indirection (which slightly speeds up undo at the expense of a more complex pack code)

  • NEO does not make any difference between object deletion and creation undone (data serial always null in storage)

  Apart from that, conversion of database back from NEO should be fixed.

Other changes are:

• A warning was added in ‘neo.conf’ about a possible misuse of replicas.

• Compatibility with Python 2.6 has been dropped.

• Support for recent version of SQlite has been added.

• A memory leak has been fixed in replication.

• MySQL backend now fails instead of silently reconnecting if there is any pending change, which could cause data loss.

• Optimization and minor bugfixes.

1.1 (2014-01-07)

• Client failed at reconnecting properly to master. It could kill the master (during tpc_finish!) or end up with invalid caches (i.e. possible data corruption). Now, connection to master is even optional between transaction.begin() and tpc_begin, as long as partition table contains up-to-date data.

• Compatibility with ZODB 3.9 has been dropped. Only 3.10.x branch is supported.

• checkCurrentSerialInTransaction was not working.

• Optimization and minor bugfixes.

1.0 (2012-08-28)

This version mainly comes with stabilized SQL tables format and efficient backup feature, relying on replication, which has been fully reimplemented:

• It is now incremental, instead of being done on whole partitions. Schema of MySQL tables have been changed in order to optimize storage layout, for good partial replication performance.

• It runs at lowest priority not to degrade performance for client nodes.

• A cluster in the new BACKINGUP state is a client to a normal cluster and all its storage nodes are notified of invalidations and replicate from upstream nodes.

Other changes are:

• Compatibility with Python < 2.6 and ZODB < 3.9 has been dropped.

• Cluster is now automatically started when all storage nodes of UP_TO_DATE cells are available, similarly to mdadm assemble --no-degraded behaviour.

• NEO learned to check replicas, to detect data corruption or bugs during replication. When done on a backup cluster, upstream data is used as reference. This is still limited to data indexes (tid & oid/serial).

• NEO logs now are SQLite DB that always contain all debugging information including exchanged packets. Records are first kept in RAM, at most 16 MB by default, and there are flushed to disk only upon RTMIN signal or any important record. A ‘neolog’ script has been written to help reading such DB.

• Master addresses must be separated by spaces. ‘/’ can’t be used anymore.

• Adding and removing master nodes is now easier: unknown incoming master nodes are now accepted instead of rejected, and nodes can be given a path to a file that maintains a list of known master nodes.

• Node UUIDs have been shortened from 16 to 4 bytes, for better performance and easier debugging.

Also contains code clean-ups and bugfixes.

0.10.1 (2012-03-13)

• Client didn’t limit its memory usage when committing big transactions.

• Master failed to disconnect clients when cluster leaves RUNNING state.

0.10 (2011-10-17)

• Storage was unable or slow to process large-sized transactions. This required to change protocol and MySQL tables format.

• NEO learned to store empty values (although it’s useless when managed by a ZODB Connection).

0.9.2 (2011-10-17)

• storage: a specific socket can be given to MySQL backend

• storage: a ConflictError could happen when client is much faster than master

• ‘verbose’ command line option of ‘neomigrate’ did not work

• client: ZODB monkey-patch randomly raised a NameError

0.9.1 (2011-09-24)

• client: method to retrieve history of persistent objects was incompatible with recent ZODB and needlessly asked all storages systematically.

• neoctl: ‘print node’ command (to get list of all nodes) raised an AssertionError.

• ‘neomigrate’ raised a TypeError when converting NEO DB back to FileStorage.

0.9 (2011-09-12)

Initial release.

NEO is considered stable enough to replace existing ZEO setups, except that:

• there’s no backup mechanism (aka efficient snapshoting): there’s only replication and underlying MySQL tools

• MySQL tables format may change in the future