We’re experimenting with a new form of release notes, so that it’s easier to get context on what’s going on in Finagle-land, especially with an eye to letting consumers see what the latest and greatest features are, and providing a little more context around what’s going on.
If you have questions about something you see in the changelogs that we didn’t mention in the expanded release notes, please feel free to email me and ask for a clarification.
At a broader level, we’d also like to mention that we’re interested in improving Java compatibility, so if you’re having trouble using one of our APIs from Java, please let us know.
We made a couple of big changes to
Buf, our byte array abstraction, and
Reader, our byte streaming abstraction. Previously, we had a special
Buf.Eof to denote the end of a byte Stream, but it occurred to us that
it didn’t make sense to have this in the byte array abstraction—it made more
sense to model it in the byte stream abstraction, so now the semantic lies in
Reader is experimental, and not used widely, so we didn’t bump
the major version. We apologize if this causes you problems.
At long last, we’ve deprecated
com.twitter.util.Bijection. This has been a
long time coming, since there’s now a fully-fledged open source
Bijection that does everything that
c.t.u.Bijection did, and a whole
We’ve added several new features to Buf, our byte array abstraction. In part,
this is to prepare to start exposing Netty-free interfaces,
so that we can swap Netty 3 out for other backends. Some of those features are
that we now have a
Buf.ByteBuffer to wrap
support reading and writing
U(32|64)(BE|LE) integers with
Bufs, and we’ve
significantly improved the performance of concatenating
There are two new features on spools as we think more about object streaming.
Spool now has take, useful for batching, and mapFuture, useful when you want
to apply a function which returns an asynchronous result to every item in your
We’ve modified the
Logging trait so that it’s more extensible, making it
easier to change the handlers for your logger. We hope that this will simplify
having a unified way of logging across a project or organization.
LoggerFactory has been hard to use from Java for a long time. We just created
LoggerFactoryBuilder, which should be much easier to use from Java. There’s
an example in the
We’re excited about making Finagle easier to use from Java, so please let us
know if you continue to run into trouble consuming Finagle from Java, so we can
work with you to make Finagle more Java-friendly.
The Scaladocs for
Flag and friends
have been significantly improved. If you ever wondered how
the Scaladocs are now an even better place to learn the nitty gritty details.
George Leontiev singlehandedly replaced all of our old specs tests with ScalaTest ones, paving the way for Util to be published against Scala 2.11. We weren’t able to publish util against 2.11 in this most recent release, but watch this space! We’re also making big strides in 2.11-ification for Finagle, in large part inspired by George’s work.
util: smattering of minor cleanups in util and finagle
util-core: Reader and getContent symmetry
util-core: Remove confusing NOOP 0.until(5) in Future.collect().
util-app: Fix a bug in global flag parsing
util-core: Fixes a broken sbt test
util-core: Log exceptions caught by ChannelStatsHandler
util-core: Satisfy promise on fatal exception in FuturePool task
util-core: small perf improvements to Future.collect, Throw, Flag
util-logging: Java-friendly LoggerFactory API
util: Update README to reflect correct storage units.
util-*: Convert all tests in util to ScalaTest
util-app: Simplifies the logic to get the appname
util-io: Buf, Reader: remove Buf.Eof; end-of-stream is None
util-io: Create Buf.ByteBuffer to wrap java.nio.ByteBuffer
util-app: Don’t kill the JVM on flag-parsing failure
util-app: Improve the Scaladocs for com.twitter.app.Flag and friends
util-core: Add U(32|64)(BE|LE) to Buf
util-core: Add com.twitter.util.NilStopwatch
util-core: Add src/main/java dependency on src/main/scala
util-core: Catch InterruptedException in Closable collector thread
util-core: Fix MockTimer#schedule(Duration)(=> Unit)‘s cancel
util-core: Fix update-after-interrupt race condition in AsyncSemaphore
util-core: Signal the deprecation of com.twitter.util.Bijection.
util-logging: Add additional handlers to Logging trait
util: Upgrade dependency versions
util-core: Scheduler productivity = cpuTime/wallTime
util-core: Add a
We’ve renamed Finagle threads, so that they are now called “finagle/netty3”. This should make it easier to figure out what is going on in your stack traces.
finagle-http now supports streaming the request body. This is not yet
documented, but there is a pull request
to add documentation to the Finagle user guide. We’d love to hear what you
Reader are two ways to retrieve the body of the HTTP message.
The previous behavior was that when the message was chunked, calling
reader.read(n) retrieved n bytes of the message body, and
returned an empty
ChannelBuffer. When the message was not chunked,
getContent returned a
ChannelBuffer filled with the message body, and
reader.read(n) was a future that never resolved. The new behavior is
that when the message is chunked, the behavior remains the same, but when not
n bytes of the message body. We
think this is behavior is much more aligned with expectations.
The previous default for inet! resolution in Finagle was to never refresh the
DNS lookup, so people had to do terrible hacks to get it to work properly. Part
of the problem was that Twitter doesn’t change DNS entries frequently, so we
don’t rely on DNS for service discovery often. However, the new Finagle
supports timer-based DNS resolution as default in
InetResolver. Thanks a ton
to Alex Gleyzer, who came up with the original
implementation, and Cobb, who got it ready to merge
Per-host stats can be too noisy to turn on in production, and will entail
significant GC pressure if you have many downstream hosts. We’ve added a new
flag that you can enable to turn on per host stats,
com.twitter.finagle.loadbalancer.perHostStats, since they are often useful for
debugging problems locally, or in staging environments.
finagle-thriftmux now supports the experimental feature GC Avoidance if you
turn on the right flags. We’re beginning to load test it now, but it’s not
ready for prime time yet. If you’re trying to use GC Avoidance outside of
Twitter, you might have a hard time. In some parts it depends upon having a JDK
System.minorGc, an extra call on
System which will only
trigger a minor GC. We’ve discussed other ways of forcing a minor GC, like
allocating a lot of big arrays very quickly, but haven’t implemented them yet.
Please get in contact if you’re interested in working on this.
We’ve significantly improved the documentation around HTTP streaming, and also added a bunch of examples. This hasn’t been merged yet, but can be found at the pull request to add documentation to the Finagle user guide. We’d love to hear what you think.
We’ve added several new stats to Finagle, to generally improve insight into
Finagle. We’ve added a
marked_dead counter to the
FailFastFactory, so that
you can see when your client perceives that downstream endpoints are flapping.
We’ve also added a couple of counters in
WatermarkPool, to make it easier to
see when you’re having queueing problems, and are asked to wait in line for a
We’ve added a service acquisition latency stat to
gives insight into how long it takes to acquire a service. Since TCP
connections are usually quite fast, and should mostly be cached, this usually
measures how long you spend queueing for a connection.
Inspired in large part by the great work in Util to get ready for Scala 2.11,
we’ve started making Finagle ready for Scala 2.11. A large part of this is
paying down technical debt that we’ve accrued, like having half of our tests
still be on specs, which is super deprecated. Because of this, we’re trying to
move as much as possible onto ScalaTest, which is what we use now.
Pierre-Antoine Ganaye, the author of the very
cool finagle-zookeeper project,
stepped up and migrated the
finagle-core tests over, while getting up to speed
on Finagle, and the Finagle community took on the mantle for the rest of the
tests. We’re over halfway
there, and we’re beginning to think about how to switch over our other projects,
like Scrooge and Twitter-server.
In order to make it easier to get new contributors started with Finagle, we’ve added sections about review process and starter issues. Also, so that open source users can see how many other open source users there are and have more confidence in our commitment to open source, we’ve started an adopters list.
finagle: Smattering of minor cleanups in util and finagle
finagle: Upgrade sbt to 0.13
finagle: Upgrade to Netty 126.96.36.199.Final
finagle-core: Add NameTree.Fail to permit failing a name without fallback
finagle-core: Add a generic DtabStatsFilter
finagle-core: Add a singleton exception and a counter in WatermarkPool
finagle-core: DefaultClient in terms of StackClient
finagle-core: Disable Netty’s thread renaming
finagle-core: Fix CumulativeGauge memory leak
finagle-core: Fix negative resolution in Namer.global
finagle-core: Fixed ChannelStatsHandler to properly filter exceptions
finagle-core: Forces finagle-core to use ipv4 network stack
finagle-core: Include path and Dtab.local in NoBrokersAvailableException
finagle-core: Log exceptions caught by ChannelStatsHandler
finagle-core: Make timer-based DNS resolution as default of InetResolver
finagle-core: Reader and getContent symmetry
finagle-core: Reduces log level for common exceptions
finagle-core: Register clients centrally
finagle-doc: Add fintop to companion projects list on Finagle website
finagle-http: Don’t emit (illegal) newlines in lengthy dtab header values
finagle-http: Fix code style from an open-source contribution
finagle-http: Migrate from specs to ScalaTest
finagle-kestrel: Make transaction abort timeout configurable in MultiReader
finagle-mux: Added extra client logging
finagle-mux: Fix broken draining behavior
finagle-mux: Improve granularity of rate to bytes/millisecond
finagle-serversets: Handle errors that occur when fetching endpoints
finagle-serversets: Increase ZK session timeout to 10 seconds
finagle-serversets: Merge WeightedSocketAddresses with same host:port but different weight in Stabilizer
finagle-serversets: Synchronize bug fixes & test coverage across ZK facades
finagle-swift: Fixes pants build warning
finagle-thrift: Add explicit dependency on libthrift
finagle-thrift: Remove usage of java_sources, should be able to depend on it normally
finagle-core: Allow trailing semicolons in dtabs
finagle-core: Rescue exceptions thrown by filter in
finagle-core: StackClient, StackClientLike don’t leak underlying In, Out types
finagle-doc: Clarify cancellation
finagle-doc: Fix broken link in document
finagle-doc: Fix name footnote in finagle Names docs
finagle-http: Buf, Reader remove Buf.Eof; end-of-stream is None
finagle-http: Prepend comment to JSONP callbacks
finagle-http: Removing specs from the CookieMapSpec test.
finagle-kestrel: Make failFast configurable in Kestrel codec
finagle-mysql: Ensure mysql specific tracing is composed.
finagle-mysql: Finagle MySQL PreparedStatement accepts Value types as params.
finagle-serversets: Identity Providers for Serverset2
finagle-thriftmux: Add withProtocolFactory API endpoint
finagle-thriftmux: Don’t reuse InMemoryStatsReceiver in the same test
finagle-*: release scrooge v3.16.0
finagle-*: release util v6.18.0
descriptionfield to com.twitter.finagle.Stackable trait
finagle-core: Add a Flag to turn on per-host stats
finagle-core: Add a service acquisition latency stat to StatsFactoryWrapper
finagle-core: Don’t support empty path elements in com.twitter.finagle.Path
finagle-core: Improves FailFastFactory documentation
finagle-core: Make c.t.f.Failure a direct subclass of Exception
finagle-core: Skip SOCKS proxy when connecting to loopback address
finagle-core: Use Monitor from caller’s context in DefaultTimer
finagle-http: Add “Enhance Your Calm” and “Too Many Requests” HTTP status codes
finagle-http: Add exp.HttpServer, which allows request limits to be configured
finagle-http: Change Request#params to a memoized def
finagle-http: Stream request body
finagle-kestrel: Add Name-based methods for MultiReader construction
finagle-memcached: Expose the client type
finagle-mux: GC Avoidance Algorithm
finagle-mux: Hook up GC avoidance to servers
finagle-mux: Move UseMux.java to the correct directory
finagle-serversets: Randomizes backoff interval in ZK2
finagle-serversets: Start resolution eagerly in ZK2
finagle-stats: Add a stat-filtration GlobalFlag
finagle-*: release ostrich v9.5.2
user guide: Add Google Analytics tracking code
user guide: Add sections about review process and starter issues
user guide: Update Finagle adopter list on user guide website
wily: Add Dtab expansion
finagle: Add list of Finagle adopters
finagle: Upgrade third-party dependencies
Addr.Negto the user guide’s list of Addr types
finagle-core: Added Failure support for sourcing to finagle
finagle-core: ClientBuilder should turn per-host stats off by default (matching new Client building API).
finagle-core: Implement DefaultServer in terms of StackServer
finagle-core: Improve the Dtab API
finagle-core: Prevent scoping stats with the empty-string
finagle-core: Rolls up the /tries scope properly
finagle-core: ServerStatsReceiver and ClientStatsReceiver can now update their root scope
finagle-core: fix race case in DelayedFactory
finagle-core: introduce AbstractResolver
finagle-core: remove need for hostConnectionLimit when using ClientBuilder#stack
finagle-core: widen to type for ServerBuilder#stack
finagle-core: widen type of ClientBuilder#stack
finagle-doc: Removed a line from conf.py
finagle-http: DtabFilter should always clear dtab headers
finagle-http: add HOST header for CONNECT method
finagle-http: scala 2.10 compatible tests
finagle-memcached: filter out one more cancelling request exception in failure accrual
finagle-memcached: remove empty test
finagle-mux: Improve Mux server close behavior, control messages to non-Mux clients
finagle-mux: Marked a gc test as flaky
finagle-mux: Modifies MuxService to essentially be a Service[Spool[Buf], Spool[Buf]] Problem
finagle-mux: Rm ClientHangupException in favor of CancelledRequestException
finagle-mysql: Retrieving a timestamp from the DB nw creates a timestamp in UTC
finagle-mysql: fix for issue where time was not being returned in UTC for binary protocol
finagle-serversets: Prevent gauges from being garbage collected
finagle-thrift: Blackhole control messages sent to non-mux Thrift clients
finagle-thriftmux: Add per-connection protocol-usage stats
finagle-thriftmux: Add stats to identify ThriftMux clients and servers
finagle-thriftmux: Propagate Contexts from non-ThriftMux clients
finagle-thriftmux: add ClientBuilder#stack compatibility and make APIs symmetric
finagle-thriftmux: pass along ClientId with ClientBuilder API
We wrote a scrooge-linter,
which we’re really excited about. If you’re at a company that has a lot of
Thrift IDL files, you know the pain of trying to get everyone to write them in a
standard way, especially since the tooling is so anemic.
begins to fix that problem, by linting your IDL files so you can catch
non-conforming thrift quickly and systematically.
The docs on how to use the scrooge tool from the command line have long been out of date. We just did a big refresher of them, and it’s much easier to get up and running with a new Scrooge project now.
scrooge-core: Add union metadata for reflection
scrooge-doc: Clarify docs on CLI usage
scrooge-generator: Fix error message for missing required field
scrooge-generator: Modify compiler to accept a Scaladoc comment at the end of Thrift file
scrooge-generator: Normalize scalatest versions between poms and 3rdparty
scrooge-generator: Stricter checks for invalid Thrift filenames
scrooge-ostrich: Default to using
scrooge-*: release finagle 6.18.0
scrooge-*: release util 6.18.0
scrooge-linter: Fix multiple arguments to linter + pants/mvn fixes
scrooge: Separate flow for linter
scrooge: Skip includes when linting
scrooge-*: Upgrade dependencies to latest versions
scrooge: Move scrooge-linter into scrooge
scrooge: Add SimpleID.originalName for enum fields
It has historically been difficult to understand how your client is configured, even though all clients are configured very similarly, usually with only small changes in parameters. However, when debugging, users sometimes need to know how long timeouts have been set to, what kind of load balancer is being used, and other configuration parameters, so that we can debug problems more quickly. Now, we have a neat admin endpoint where users can gain insight into each client individually.
Having logging at multiple granularities is a real luxury, but sometimes you realize that you’ve set the log level incorrectly, and you need to be able to see more granular logs on a box that’s already in an interesting state, in production. To that end, we’ve added a logging handler to the Twitter-server admin service, which can both tell you about the current log levels, but can also be used to change logging granularities on the fly.
We added a new admin handler to display the base dtab, so that it’s easier to reason about what will happen to a service when it receives a new dtab. Instead of having to guess based on its behavior, or try to figure it out through inspecting the code, you can just query now, and know the right answer immediately.
Built-in metrics are one of the coolest features of Finagle, but there are
really a ton of them, especially if you have many downstreams, or you use per
host stats. In order to make this problem easier to deal with, we added a flag,
com.twitter.finagle.stats.statsFilter, which you can pass in to filter out
some stats that you know you will never use.