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Release Notes

Watchman is continuously deployed inside Facebook, which means that we don't explicitly maintain version numbers. We have automation that cuts a weekly tag with a named derived from the date. You can learn more about how to reason about supported capabilities and our backwards compatibility guidelines in the Compatibility Rules docs.

We focus on the highlights only in these release notes. For a full history that includes all of the gory details, please see the commit history on GitHub.

Watchman v2020.07.13.00​

  • Added script watchman-replicate-subscription. It can replicate an existing watchman subscription. Integrators can use this script to validate watchman notifications their client is receiving.
  • Added support for suffix sets in suffix expressions. You now can specify multiple suffixes to match against by setting the second argument to a list of suffixes. See suffix-set documentation for more details
  • pywatchman: introduced new pywatchman_aio client for python
  • Windows: we no longer trust environment variables to locate the state directory which should result in a better experience for users that mix cygwin, mingw, native windows and/or WSL or other environments
  • Windows: we now support unix domain sockets on Windows 10. The CLI will prefer to use unix domain sockets when available.

We weren't great at updating the release notes since the prior release; there was a lot of work to support our sister project EdenFS that isn't broadly relevant to those outside FB at the time of writing.

Watchman 4.9.0 (2017-08-24)​

  • New field: content.sha1hex. This field expands to the SHA1 hash of the file contents, expressed in hex digits (40 character hex string). Watchman maintains a cache of the content hashes and can compute the hash on demand and also heuristically as files are changed. This is useful for tooling that wants to perform more intelligent cache invalidation or build artifact fetching from content addressed storage.
  • Experimental feature: Source Control Aware query mode. Currently supports only Mercurial (patches to add Git support are welcomed!). SCM aware query mode helps to keep response sizes closer to O(what-you-changed) than to O(all-repo-changes) when rebasing your code. Using this feature effectively may require some additional infrastructure to compute and associate data with revisions from your repo.
  • Fixed an issue that resulted in the perf logging thread deadlocking when perf_logger_command is enabled in the global configuration
  • Fixed an issue where queries larger than 1MB would likely result in a PDU error response.
  • Reduced lock contention for subscriptions that do no use the advanced settling (drop, defer) options.
  • Fixed since generator behavior when using unix timestamps rather than the preferred clock string syntax
  • Improved the reporting of "new" files in watchman results
  • Improved performance of handling changes on case insensitive filesystems
  • Windows: promoted from alpha to beta status!
  • Windows: fixed some performance and reliability issues
  • Windows: now operates correctly on Windows 7
  • Windows: can now see and report symlinks and junction points
  • Windows: fixed potential deadlock in trigger deletion
  • Windows: fixed stack trace rendering on win32
  • Windows: improved IO scheduling around deletes on win32
  • Windows: improved handling of case insensitive win32 driver letters
  • pywatchman: the python wheel format is used for publishing watchman pypi package
  • pywatchman: now watchman path is configurable in python client
  • pywatchman: now python client can be used as a context manager
  • Solaris: support for Solaris has been removed. If you'd like to commit to testing and maintaining Solaris support, we'd love to hear from you!

Watchman 4.8.0 (never formally released)​

Whoops, we never got around to tagging this beyond a release candidate tag!

  • New command flush-subscriptions to synchronize subscriptions associated with the current session.
  • On Windows, return / as the directory separator. Previously we used \. This change should be pretty neutral for clients, and makes it easier to work with both the internals and the integration test infrastructure.
  • Enforce socket Unix groups more strongly — Watchman will now refuse to start if it couldn't gain the right group memberships, as can happen for sites that are experiencing intermittent LDAP connectivity problems.
  • pywatchman now officially supports Python 3. pywatchman will return Unicode strings (possibly with surrogate escapes) by default, but can optionally return bytestrings. Note that on Python 3, pywatchman requires Watchman 4.8 and above. The Python 2 interface and requirements remain unchanged.
  • Prior to 4.8, methods on the Java WatchmanClient that returned ListenableFutures would swallow exceptions and hang in an unfinished state under situations like socket closure or thread death. This has been fixed, and now ListenableFutures propagate exception conditions immediately. (Note that this is typically unrecoverable, and users should create a new WatchmanClient to re-establish communication with Watchman.) See #412.
  • The minimum Java version for the Watchman Java client has always been 1.7, but it was incorrectly described to be 1.6. The Java client's build file has been fixed accordingly.
  • Watchman was converted from C to C++. The conversion exposed several concurrency bugs, all of which have now been fixed.
  • Subscription queries are now executed in the context of the client thread, which means that subscriptions are dispatched in parallel. Previously, subscriptions would be serially dispatched and block the disk IO thread.
  • Triggers are now dispatched in parallel and waits are managed in their own threads (one thread per trigger). This improves concurrency and resolves a couple of waitpid related issues where watchman may not reap spawned children in a timely fashion, or may spin on CPU until another child is spawned.
  • Fixed an object lifecycle management issue that could cause a crash when aging out old/transient files.
  • Implement an upgraded wire protocol, BSERv2, on the server and in pywatchman. BSERv2 can carry information about string encoding over the wire. This lets pywatchman convert to Unicode strings on Python 3. Clients and servers know how to transparently fall back to BSERv1.
  • OS X: we no longer use socket activation when registering with launchd. This was the source of some upgrade problems for mac Homebrew users.

Watchman 4.7.0 (2016-09-10)​

  • Reduced memory usage by 40%
  • Queries can now run with a shared lock. It is recommended that clients move away from the n:FOO style server side named cursor clockspecs to take full advantage of this.
  • Added new glob generator as a walking strategy for queries. This allows watchman to evaluate globs in the most efficient manner. Our friends in the Buck project have already integrated this into their BUCK file parsing to evaluate globs without touching the filesystem!
  • Added "case_sensitive": true option to queries to force matches to happen in a case sensitive manner, even if the watched root is on a case insensitive filesystem. This is used to accelerate certain types of internal traversal: if we know that a path is case sensitive we can perform an O(1) lookup where we would otherwise have to perform an O(number-of-directory-entries) scan and compare.
  • Fixed a race condition during subscription initiation that could emit incorrect clock values.
  • Fixed spurious over-notification for parent directories of changed files on Mac.
  • Fixed some reliability issues on Windows

Watchman 4.6.0 (2016-07-09)​

  • Improved I/O scheduling when processing recursive deletes and deep directory rename operations.
  • Improved performance of the ignore_dirs configuration option on OS X and Windows systems. We take advantage of an undocumented (but supported!) API to further accelerate this for the first 8 entries in the ignore_dirs on OS X. Users that depend on this configuration to avoid recrawls will want to review and prioritize their most active build dirs to the front of the ignore_dirs specified in their .watchmanconfig file.
  • Added an optional recrawl recovery strategy for OS X that will attempt to resync from the fseventsd journal rather than performing a full filesystem walk. This is currently disabled by default but will likely be enabled by default in the next Watchman release. You can enable this by setting fsevents_try_resync: true in either /etc/watchman.json or your .watchmanconfig. This should reduce the frequency of recrawl warnings for some users/workloads, and also improves I/O for users with extremely large trees.
  • Fixed accidental exponential time complexity issue with recursive deletes and deep directory rename operations on case-insensitive filesystems (such as OS X). This manifested as high CPU utilization for extended periods of time.
  • Added support for allowing non-owner access to a Watchman instance. Only the owner is authorized to create or delete watches. Non-owners can view information about existing watches. Access control is based on unix domain socket permissions. The new but not yet documented configuration options sock_group and sock_access can be used to control this new behavior.
  • Added support for inetd-style socket activation of the watchman service. this commit includes a sample configuration for systemd.
  • Added the symlink_target field to the stored metadata for files. This holds the text of the symbolic link for symlinks. You can test whether it is supported by a watchman server using the capability name field-symlink_target.
  • Fixed an issue where watchman may not reap child processes spawned by triggers.
  • Fixed an issue where watchman may block forever during shutdown if there are other connected clients.
  • Added hint_num_dirs configuration option.

pywatchman 1.4.0 (????-??-??)​

(These changes have not yet been released to pypi)

  • Added immutable version of data results to bser. This is cheaper to build from a serialized bser representation than the mutable version and is better suited to large result sets received from watchman.
  • Fixed a number of misc. portability issues
  • Added Python 3.x support

Watchman 4.5.0 (2016-02-18)​

  • Fixed an inotify race condition for non-atomic directory replacements that was introduced in Watchman 4.4.

Watchman 4.4.0 (2016-02-02)​

  • Added state-enter and state-leave commands can allow subscribers to more intelligently settle/coalesce events around hg update or builds.
  • Fixed an issue where subscriptions could double-notify for the same events.
  • Fixed an issue where subscriptions that never match any files add O(all-observed-files) CPU cost to every subscription dispatch

Watchman 4.3.0 (2015-12-14)​

  • Improved handling of case insensitive renames; halved the memory usage and doubled crawl speed on OS X.

Watchman 4.2.0 (2015-12-08)​

  • Increased strictness of checks for symlinks; rather than just checking whether the leaf of a directory tree is a symlink, we now check each component down from the root of the watch. This improves detection and processing for directory-to-symlink (and vice versa) transitions.
  • Increased priority of the watchman process on OS X.

pywatchman 1.3.0 (2015-10-22)​

  • Added watchman-make and watchman-wait commands
  • Added pure python implementation of BSER

Watchman 4.1.0 (2015-10-20)​

  • Fixed an issue where symlink size was always reported as 0 on OS X using the new bulkstat functionality

Watchman 4.0.0 (2015-10-19)​

  • Fixed an issue where a directory that was replaced by a symlink would cause a symlink traversal instead of correctly updating the type of the node and marking the children removed.
  • Fixed a debugging log line that was emitted at the wrong log level on every directory traversal.

Watchman 3.9.0 (2015-10-12)​

  • Fixed an issue where dir renames on OS X could cause us to lose track of the files inside the renamed dir
  • Fixed an issue where dir deletes and replacements on Linux could cause us to lose track of the files inside the replaced dir (similar to the OS X issue above in manifestation, but a different root cause).
  • Improved (re)crawl speed for dirs with more than a couple of entries on average (improvement can be up to 5x for dirs with up to 64 entries on average). You may now tune the hint_num_files_per_dir setting in your .watchmanconfig to better match your tree. More details
  • Improved (re)crawl speed on OS X 10.10 and later by using getattrlistbulk. This allows us to improve the data:syscall ratio during crawling and can improve throughput by up to 40% for larger trees.
  • Add optional sync_timeout to the clock command
  • Avoid accidentally passing descriptors other than the stdio streams when we spawn the watchman service.
  • Fixed a race condition where we could start two sets of watcher threads for the same dir if two clients issue a watch or watch-project at the same time
  • Added a helpful error for a tmux + launchd issue on OS X

Watchman 3.8.0 (2015-09-14)​

  • Improved latency of processing kernel notifications. It should now be far less likely to run into an notification queue overflow.
  • Improved idle behavior. There were a couple of places where watchman would wake up more often than was strictly needed and these have now been fixed. This is mostly of interest to laptop users on battery power.
  • Improved inotify move tracking. Some move operations could cause watchman to become confused and trigger a recrawl. This has now been resolved.
  • Hardened statedir and permissions. There was a possibility of a symlink attack and this has now been mitigated by re-structuring the statedir layout.
  • Fixed a possible deadlock in the idle watch reaper
  • Fixed an issue where the watchman -p log-level debug could drop log notifications in the CLI
  • Disabled the IO-throttling-during-crawl that we added in 3.7. It proved to be more harmful than beneficial.
  • -j CLI option now accepts either JSON or BSER encoded command on stdin
  • Added capabilities to the server, and added the capabilityCheck method to the python and node clients.

pywatchman 1.2.0 (2015-08-15)​

  • Added the capabilityCheck method
  • Added SocketTimeout exception to distinguish timeouts from protocol level exceptions

fb-watchman 1.3.0 for node (2015-08-15)​

pywatchman 1.0.0 (2015-08-06)​

  • First official pypi release, thanks to @kwlzn for setting up the release machinery for this.

Watchman 3.7.0 (2015-08-05)​

(Watchman 3.6.0 wasn't formally released)

  • Fixed bug where query match on foo*.java with wholename scope would incorrectly match foo/bar/baz.java.
  • Added src/**/*.java recursive glob pattern support to query match.
  • Added options dictionary to query's match operator.
  • Added includedotfiles option to query match to include files whose names start with ..
  • Added noescape option to query match to make \ match literal \.
  • We'll now automatically age out and stop watches. See idle_reap_age_seconds for more information.
  • watch-project will now try harder to re-use an existing watch and avoid creating an overlapping watch.
  • Reduce I/O priority during crawling on systems that support this
  • Fixed issue with the long long data type in the python BSER module

fb-watchman 1.2.0 for node (2015-07-11)​

  • Updated the node client to more gracefully handle undefined values in objects when serializing them; we now omit keys whose values are undefined rather than throw an exception.

Watchman 3.5.0 (2015-06-29)​

  • Fix the version number reported by watchman.

Watchman 3.4.0 (2015-06-29)​

  • trigger now supports an optional relative_root argument. The trigger is evaluated with respect to this subdirectory. See trigger for more.

fb-watchman 1.1.0 for node (2015-06-25)​

  • Updated the node client to handle 64-bit integer values using the node-int64. These are most likely to show up if your query fields include size and you have files larger than 2GB in your watched root.

fb-watchman 1.0.0 for node (2015-06-23)​

  • Updated the node client to support BSER encoding, fixing a quadratic performance issue in the JSON stream decoder that was used previously.

Watchman 3.3.0 (2015-06-22)​

  • query and subscribe now support an optional relative_root argument. Inputs and outputs are evaluated with respect to this subdirectory. See File Queries for more.