Apply a patch to add snooze_period_ms for finer tuning

See apache/couchdb#1880

0002-Compaction-Add-snooze_period_ms-for-finer-tuning.patch

@@ -0,0 +1,161 @@
+From 0447a04bc71df897015722bc57a5f499cdcfab2a Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Adrien=20Verg=C3=A9?= <adrienverge@gmail.com>
+Date: Mon, 28 Jan 2019 10:43:43 +0100
+Subject: [PATCH] Compaction: Add snooze_period_ms for finer tuning
+
+We are experiencing an issue similar to #1579, partly because we have
+dozens of thousands of databases.
+
+On our servers:
+- `snooze_period = 0` leads to a significant CPU load,
+- `snooze_period = 1` is too long for compaction to finish within 20
+  hours (after 20 hours, compaction is stopped to allow other
+  CPU-intensive processes to run, and when compaction restarts, it does
+  not pick up where it left 4 hours earlier -- by the way proposal at
+  #1775 would be really great to fix that!)
+
+This commit introduces a new option `snooze_period_ms` (measured in
+milliseconds), and deprecates `snooze_period` while still supporting it
+for obvious legacy reasons.
+---
+ rel/overlay/etc/default.ini                   |  7 +-
+ src/couch/src/couch_compaction_daemon.erl     | 71 +++++++++++++++++--
+ .../test/couchdb_compaction_daemon_tests.erl  |  2 +-
+ 3 files changed, 72 insertions(+), 8 deletions(-)
+
+diff --git a/rel/overlay/etc/default.ini b/rel/overlay/etc/default.ini
+index b9d51af71..24428f3e5 100644
+--- a/rel/overlay/etc/default.ini
++++ b/rel/overlay/etc/default.ini
+@@ -415,9 +415,10 @@ min_file_size = 131072
+ ; With lots of databases and/or with lots of design docs in one or more
+ ; databases, the compaction_daemon can create significant CPU load when
+ ; checking whether databases and view indexes need compacting. The
+-; snooze_period setting ensures a smoother CPU load. Defaults to
+-; 3 seconds wait.
+-; snooze_period = 3
++; snooze_period_ms setting ensures a smoother CPU load. Defaults to
++; 3000 milliseconds wait. Note that this option was formerly called
++; snooze_period, measured in seconds (it is currently still supported).
++; snooze_period_ms = 3000
+
+ [compactions]
+ ; List of compaction rules for the compaction daemon.
+diff --git a/src/couch/src/couch_compaction_daemon.erl b/src/couch/src/couch_compaction_daemon.erl
+index 115a9a897..2a46c3f26 100644
+--- a/src/couch/src/couch_compaction_daemon.erl
++++ b/src/couch/src/couch_compaction_daemon.erl
+@@ -125,8 +125,16 @@ handle_config_terminate(_, stop, _) ->
+ handle_config_terminate(_Server, _Reason, _State) ->
+     erlang:send_after(?RELISTEN_DELAY, whereis(?MODULE), restart_config_listener).
+
++get_snooze_period() ->
++    % The snooze_period_ms option should be used, but snooze_period is supported
++    % for legacy reasons.
++    Default = config:get_integer("compaction_daemon", "snooze_period", 3),
++    case config:get_integer("compaction_daemon", "snooze_period_ms", -1) of
++        -1 -> Default * 1000;
++        SnoozePeriod -> SnoozePeriod
++    end.
++
+ compact_loop(Parent) ->
+-    SnoozePeriod = config:get_integer("compaction_daemon", "snooze_period", 3),
+     {ok, _} = couch_server:all_databases(
+         fun(DbName, Acc) ->
+             case ets:info(?CONFIG_ETS, size) =:= 0 of
+@@ -140,7 +148,7 @@ compact_loop(Parent) ->
+                     case check_period(Config) of
+                     true ->
+                         maybe_compact_db(Parent, DbName, Config),
+-                        ok = timer:sleep(SnoozePeriod * 1000);
++                        ok = timer:sleep(get_snooze_period());
+                     false ->
+                         ok
+                     end
+@@ -231,8 +239,7 @@ maybe_compact_views(DbName, [DDocName | Rest], Config) ->
+         timeout ->
+             ok
+         end,
+-        SnoozePeriod = config:get_integer("compaction_daemon", "snooze_period", 3),
+-        ok = timer:sleep(SnoozePeriod * 1000);
++        ok = timer:sleep(get_snooze_period());
+     false ->
+         ok
+     end.
+@@ -597,4 +604,60 @@ abs_path2_test() ->
+     ?assertEqual({ok, "/a/b/"}, abs_path2("/a/b")),
+     ok.
+
++get_snooze_period_test_() ->
++    {
++        foreach,
++        fun() ->
++            meck:new(config, [passthrough])
++        end,
++        fun(_) ->
++            meck:unload()
++        end,
++        [
++            {"should return default value without config attributes",
++            fun should_default_without_config/0},
++            {"should respect old config attribute",
++            fun should_respect_old_config/0},
++            {"should respect old config set to zero",
++            fun should_respect_old_config_zero/0},
++            {"should respect new config attribute",
++            fun should_respect_new_config/0},
++            {"should respect new config set to zero",
++            fun should_respect_new_config_zero/0}
++        ]
++    }.
++
++should_default_without_config() ->
++    ?assertEqual(3000, get_snooze_period()).
++
++should_respect_old_config() ->
++    meck:expect(config, get_integer, fun
++        ("compaction_daemon", "snooze_period", _) -> 1;
++        (_, _, Default) -> Default
++    end),
++    ?assertEqual(1000, get_snooze_period()).
++
++should_respect_old_config_zero() ->
++    meck:expect(config, get_integer, fun
++        ("compaction_daemon", "snooze_period", _) -> 0;
++        (_, _, Default) -> Default
++    end),
++    ?assertEqual(0, get_snooze_period()).
++
++should_respect_new_config() ->
++    meck:expect(config, get_integer, fun
++        ("compaction_daemon", "snooze_period", _) -> 1;
++        ("compaction_daemon", "snooze_period_ms", _) -> 300;
++        (_, _, Default) -> Default
++    end),
++    ?assertEqual(300, get_snooze_period()).
++
++should_respect_new_config_zero() ->
++    meck:expect(config, get_integer, fun
++        ("compaction_daemon", "snooze_period", _) -> 1;
++        ("compaction_daemon", "snooze_period_ms", _) -> 0;
++        (_, _, Default) -> Default
++    end),
++    ?assertEqual(0, get_snooze_period()).
++
+ -endif.
+diff --git a/src/couch/test/couchdb_compaction_daemon_tests.erl b/src/couch/test/couchdb_compaction_daemon_tests.erl
+index c10ddee12..0ef2a4064 100644
+--- a/src/couch/test/couchdb_compaction_daemon_tests.erl
++++ b/src/couch/test/couchdb_compaction_daemon_tests.erl
+@@ -24,7 +24,7 @@
+ start() ->
+     Ctx = test_util:start_couch(),
+     ok = config:set("compaction_daemon", "check_interval", "3", false),
+-    ok = config:set("compaction_daemon", "snooze_period", "0", false),
++    ok = config:set("compaction_daemon", "snooze_period_ms", "0", false),
+     ok = config:set("compaction_daemon", "min_file_size", "100000", false),
+     ok = config:delete("compactions", "_default", false),
+     ok = meck:new(?MODS_TO_MOCK, [passthrough]),
+-- 
+2.20.1
+

couchdb.spec

@@ -8,7 +8,7 @@
 
 Name:          couchdb
 Version:       2.3.0
-Release:       1%{?dist}
+Release:       2%{?dist}
 Summary:       A document database server, accessible via a RESTful JSON API
 Group:         Applications/Databases
 License:       Apache
@@ -17,6 +17,7 @@ Source0:       http://apache.mirrors.ovh.net/ftp.apache.org/dist/couchdb/source/
 Source1:       %{name}.service
 Source2:       usr-bin-couchdb
 Patch1:        0001-Read-config-from-env-COUCHDB_VM_ARGS-and-COUCHDB_INI.patch
+Patch2:        0002-Compaction-Add-snooze_period_ms-for-finer-tuning.patch
 
 %if 0%{?rhel}
 # Needs packages.erlang-solutions.com repo in /etc/mock/epel-7-x86_64.cfg,
@@ -48,6 +49,7 @@ JavaScript acting as the default view definition language.
 %prep
 %setup -q -n apache-couchdb-%{version}
 %patch1 -p1
+%patch2 -p1
 
 
 %build
@@ -107,6 +109,9 @@ getent passwd %{name} >/dev/null || \
 
 
 %changelog
+* Mon Jan 28 2019 Adrien Vergé <adrienverge@gmail.com> 2.3.0-2
+- Apply a patch to add snooze_period_ms for finer tuning, see https://github.com/apache/couchdb/pull/1880
+
 * Tue Dec 11 2018 Adrien Vergé <adrienverge@gmail.com> 2.3.0-1
 - Update to new upstream version (skip 2.2 that has bugs)
 - Customizing args file is now supported upstream