> On March 10, 2015, 8:35 a.m., Benjamin Hindman wrote:
> > src/launcher/fetcher.cpp, lines 403-404
> > <https://reviews.apache.org/r/30774/diff/33/?file=888350#file888350line403>
> > As mentioned above, it would be great to really capture the
> > relationship between the FetcherInfo and the FetcherInfo::Item. If The
> > FetcherInfo encapsulates the FetcherInfo::Item I would also suggest
> > switching the order of the parameters to signify that.
> Bernd Mathiske wrote:
> The main purpose here is to fetch this one particular item, not
> everything FetcherInfo carries. FetcherInfo is a secondary parameter that
> provides extra parameters like cache_directory, sandbox_directory, and
> framework_home. Putting it second makes this relationship clear IMHO. Do you
> suggest adding all these as individual parameters?
> Yes, the item is included in the list of items in FetcherInfo. Shall we
> break up FetcherInfo into several shells, the inner one without items?
Now using split up parameters instead of FetcherInfo to pass around sandbox
dir, cache dir, frameworks home.
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On April 30, 2015, 7:40 p.m., Bernd Mathiske wrote:
> This is an automatically generated e-mail. To reply, visit:
> (Updated April 30, 2015, 7:40 p.m.)
> Review request for mesos, Adam B, Benjamin Hindman, Till Toenshoff, and
> Timothy Chen.
> Bugs: MESOS-2057, MESOS-2069, MESOS-2070, MESOS-2072, MESOS-2073, and
> Repository: mesos
> Almost all of the functionality in epic MESOS-336. Downloaded files from
> CommandInfo::URIs can now be cached in a cache directory designated by a
> slave flag. This only happens when asked for by an extra flag in the URI and
> is thus backwards-compatible. The cache has a size limit also given by a new
> slave flag. Cache-resident files are evicted as necessary to make space for
> newly fetched ones. Concurrent attempts to cache the same URI leads to only
> one download. The fetcher program remains external for safety reasons, but is
> now augmented with more elaborate parameters packed into a JSON object to
> implement specific fetch actions for all of the above. Additional testing
> includes fetching from (mock) HDFS and coverage of the new features.
> docs/configuration.md 54c4e31ed6dfed3c23d492c19a301ce119a0519b
> docs/fetcher-cache-internals.md PRE-CREATION
> docs/fetcher.md PRE-CREATION
> include/mesos/mesos.proto 967b1e3bbfb3f6b71d5a15d02cba7ed5ec21816f
> include/mesos/type_utils.hpp 044637481e5405d4d6f61653a9f9386edd191deb
> src/Makefile.am 93c7c8a807a33ab639be6289535bbd32022aa85b
> src/hdfs/hdfs.hpp 968545d9af896f3e72e156484cc58135405cef6b
> src/launcher/fetcher.cpp 796526f59c25898ef6db2b828b0e2bb7b172ba25
> src/slave/constants.hpp fd1c1aba0aa62372ab399bee5709ce81b8e92cec
> src/slave/containerizer/docker.hpp b25ec55bf3cd30d6e8a804d09d90c632a7d12e3f
> src/slave/containerizer/docker.cpp f9fc89ad7e3c853c3f9f6dcf9aa68e54dc1888c6
> src/slave/flags.hpp d3b1ce117fbb4e0b97852ef150b63f35cc991032
> src/slave/flags.cpp d0932b04e3825abb6173efe0d1aee199aa356932
> src/slave/slave.cpp c78ee3c9e7fc38ad364e83f4abe267e86bfbbc13
> src/tests/fetcher_cache_tests.cpp PRE-CREATION
> src/tests/fetcher_tests.cpp 4549e6a631e2c17cec3766efaa556593eeac9a1e
> src/tests/mesos.hpp 19db71217f0a3f1ab17a6fd4408f8251410d731d
> src/tests/mesos.cpp bc082e8d91deb2c5dd64bbc3f0a8a50fa7d19264
> Diff: https://reviews.apache.org/r/30774/diff/
> make check
> --- longer Description: ---
> -Replaces all other reviews for the fetcher cache except those related to
> stout: 30006, 30033, 30034, 30036, 30037, 30039, 30124, 30173, 30614, 30616,
> 30618, 30621, 30626. See descriptions of those. In dependency order:
> 30033: Removes the fetcher env tests since these won't be needed any more
> when the fetcher uses JSON in a single env var as a parameter. They never
> tested anything that won't be covered by other tests anyway.
> 30034: Makes the code structure of all fetcher tests the same. Instead of
> calling the run method of the fetcher directly, calling through fetch(). Also
> removes all uses of I/O redirection, which is not really needed for
> debugging, and thus the next patch can refactor fetch() and run(). (The
> latter comes in two varieties, which complicates matters without much
> 30036: Extends the CommandInfo::URI protobuf with a boolean "caching" field
> that will later cause fetcher cache actions. Also introduces the notion of a
> cache directory to the fetcher info protobuf. And then propagates these
> additions throughout the rest of the code base where applicable. This
> includes passing the slave ID all the way down to the place where the cache
> dir name is constructed.
> 30037: Extends the fetcher info protobuf with "actions" (fetch directly
> bypassing the cache, fetch through the cache, retrieve from the cache).
> Switches the basis for dealing with uris to "items", which contain the uri,
> the action, and potentially a cache file name. Refactors fetch() and run(),
> so there is only one of each. Introduces about half of the actual cache
> logic, including a hashmap of cache file objects for bookkeeping and basic
> operations on it.
> 30039: Enables fetcher cache actions in the mesos fetcher program.
> 30006: Enables concurrent downloading into the fetcher cache. Reuse of
> download results in the cache when multiple fetcher runs occur concurrently.
> 30614: This is to ensure that all this refactoring of fetcher code has not
> broken HDFS fetching. Adds a test that exercises the C++ code paths in Mesos
> and mesos-fetcher related to fetching from HDFS. Uses a mock HDFS client
> written in bash that acts just like a real "hadoop" command if used in the
> right limited way.
> 30124: Inserted fetcher cache zap upon slave startup, recovery and shutdown.
> This implements recovery in an acceptable, yet most simple way.
> 30173: Created fetcher cache tests. Adds a new test source file containing a
> test fixture and tests to find out if the fetcher cache works with a variety
> of settings.
> 30616: Adds hdfs::du() which calls "hadoop fs -du -h" and returns a string
> that contains the file size for the URI passed as argument. This is needed to
> determine the size of a file on HDFS before downloading it to the fetcher
> cache (to ensure there is enough space).
> 30621: Refactored URI type separation in mesos-fetcher. Moved the URI type
> separation code (distinguishes http, hdfs, local copying, etc.) from
> mesos-fetcher to the fetcher process/actor, since it is going to be reused by
> download size queries when we introduce fetcher cache management. Also
> factored out URI validation, which will be used the same way by mesos-fetcher
> and the fetcher process/actor.
> 30626: Fetcher cache eviction. This happens when the cache does not have
> enough space to accomodate upcoming downloads to the cache. Necessary
> provisions included here:
> - mesos-fetcher does not run until evictions have been successful
> - Cache space is reserved while (async) waiting for eviction to succeed. If
> it fails, the reservation gets undone.
> - Reservations can be partly from available space, partly from evictions. All
> math included :-)
> - To find out how much space is needed, downloading has a prelude in which we
> query the download size from the URI. This works for all URI types that
> mesos-fetcher currently supports, including http and hdfs.
> - Size-determination requests are now synchronized, too. Only one per URI in
> play happens.
> - There is cleanup code for all kinds of error situations. At the very end of
> the fetch attempt, each list is processed for undoing things like space
> reservations and eviction disabling.
> - Eviction gets disabled for URIs that are currently in use, i.e. the related
> cache files are. We use reference counting for this, since there may be
> concurrent fetch attempts using the same cache files.
> Bernd Mathiske