[tarantool-patches] Re: [PATCH][vshard] Reload reloadable fiber
Vladislav Shpilevoy
v.shpilevoy at tarantool.org
Wed Jun 27 14:34:17 MSK 2018
Please, rebase on the latest master branch. When I do,
the tests fail.
On 27/06/2018 13:44, Alex Khatskevich wrote:
>
>
> On 27.06.2018 12:54, Vladislav Shpilevoy wrote:
>> Hello. Thanks for the fixes! See 4 comments below.
>>
>> On 26/06/2018 15:50, Alex Khatskevich wrote:
>>> Sorry, I forgot to put the new patch here
>>>
>>> commit 4ddab3c47c5963c3138701d89ba3091d5da9848a
>>> Author: AKhatskevich <avkhatskevich at tarantool.org>
>>> Date: Thu Jun 14 14:03:07 2018 +0300
>>>
>>> Reload reloadable fiber
>>>
>>> Fixed a problem:
>>> The `reloadable_fiber_f` was running an infinite while loop and
>>> preventing the whole module from being reloaded.
>>>
>>> This behavior is fixed by calling new version of `reloadable_fiber_f` in
>>> a return statement instead of the where loop. Note: calling a function
>>
>> 1. Again 'where loop'.
>>
> Sorry
>>> in a return statement doesn't increase a stack size.
>>>
>>> Extra changes:
>>> * transfer write "started" message responsibility from caller to
>>> reloadable fiber
>>>
>>> Closes #116
>>>
>>> diff --git a/test/unit/util.result b/test/unit/util.result
>>> new file mode 100644
>>> index 0000000..dbfcce9
>>> --- /dev/null
>>> +++ b/test/unit/util.result
>>> @@ -0,0 +1,72 @@
>>> +test_run = require('test_run').new()
>>> +---
>>> +...
>>> +fiber = require('fiber')
>>> +---
>>> +...
>>> +log = require('log')
>>> +---
>>> +...
>>> +test_util = require('util')
>>> +---
>>> +...
>>> +util = require('vshard.util')
>>> +---
>>> +...
>>> +test_run:cmd("setopt delimiter ';'")
>>> +---
>>> +- true
>>> +...
>>> +fake_M = {
>>> + reloadable_func = nil,
>>> + module_version = 1,
>>> +};
>>> +---
>>> +...
>>> +test_run:cmd("setopt delimiter ''");
>>> +---
>>> +- true
>>> +...
>>> +-- Check autoreload on function change during failure.
>>> +fake_M.reloadable_function = function () fake_M.reloadable_function = 42; error('Error happened.') end
>>> +---
>>> +...
>>> +fib = fiber.create(util.reloadable_fiber_f, fake_M, 'reloadable_function', 'Worker_name')
>>> +---
>>> +...
>>> +fib:cancel()
>>> +---
>>> +...
>>> +test_run:grep_log('default', 'Worker_name: reloadable function reloadable_function has changed')
>>
>> 2. 'Has been' changed?
> I has changed it, but there are two notes:
> 1. Both are correct https://english.stackexchange.com/questions/97243/has-been-changed-or-has-changed
> 2. vshard uses both options:
> a. "Configuration has changed, restart"
> b. "Rebalancer location has changed"
>>
>>> +---
>>> +- 'Worker_name: reloadable function reloadable_function has changed'
>>> +...
>>> diff --git a/vshard/util.lua b/vshard/util.lua
>>> index bb71318..920f53e 100644
>>> --- a/vshard/util.lua
>>> +++ b/vshard/util.lua
>>> @@ -19,33 +32,37 @@ local function tuple_extract_key(tuple, parts)
>>> +local function reloadable_fiber_f(module, func_name, worker_name)
>>> + log.info('%s has been started', worker_name)
>>> + local func = module[func_name]
>>> + local ok, err = pcall(func, module.module_version)
>>> + if not ok then
>>> + log.error('%s has been failed: %s', worker_name, err)
>>> + if func ~= module[func_name] then
>>> + log.warn('%s: reloadable function %s has changed',
>>> + worker_name, func_name)
>>
>> 3. Why is these check and warn here, after an error?
> Changed:
> 1. warn -> error
> 2. Comment added:
> -- There is a chance that error was raised during reload
> -- (or caused by reload). Perform reload in case function
> -- has been changed.
>>
>>> end
>>> end
>>> + -- yield serves two pursoses:
>>> + -- * makes this fiber cancellable
>>> + -- * prevents 100% cpu consumption
>>> + fiber.yield()
>>> + log.info('%s is reloaded, restarting', worker_name)
>>
>> 4. Why do you print 'is reloaded' even if it just thrown an error
>> and the function is not changed actually?
>
> Fixed by goto
>>
>>> + -- luajit drops this frame if next function is called in
>>> + -- return statement.
>>> + return M.reloadable_fiber_f(module, func_name, worker_name)
>>> end
>
> Full diff:
>
> commit d098bf0930935b029fbca3f4fd78211dd5022fb1
> Author: AKhatskevich <avkhatskevich at tarantool.org>
> Date: Thu Jun 14 14:03:07 2018 +0300
>
> Reload reloadable fiber
>
> Fixed a problem:
> The `reloadable_fiber_f` was running an infinite while loop and
> preventing the whole module from being reloaded.
>
> This behavior is fixed by calling new version of `reloadable_fiber_f` in
> a return statement instead of the while loop. Note: calling a function
> in a return statement doesn't increase a stack size.
>
> Extra changes:
> * transfer write "started" message responsibility from caller to
> reloadable fiber
>
> Closes #116
>
> diff --git a/test/rebalancer/rebalancer.result b/test/rebalancer/rebalancer.result
> index 22100fe..6e3aa81 100644
> --- a/test/rebalancer/rebalancer.result
> +++ b/test/rebalancer/rebalancer.result
> @@ -424,7 +424,7 @@ vshard.storage.cfg(cfg, names.replica_uuid.box_2_b)
> fiber = require('fiber')
> ---
> ...
> -while not test_run:grep_log('box_2_a', "Run rebalancer") do fiber.sleep(0.1) end
> +while not test_run:grep_log('box_2_a', "Rebalancer has been started") do fiber.sleep(0.1) end
> ---
> ...
> while not test_run:grep_log('box_1_a', "Rebalancer location has changed") do fiber.sleep(0.1) end
> diff --git a/test/rebalancer/rebalancer.test.lua b/test/rebalancer/rebalancer.test.lua
> index 3327f30..922357a 100644
> --- a/test/rebalancer/rebalancer.test.lua
> +++ b/test/rebalancer/rebalancer.test.lua
> @@ -197,7 +197,7 @@ switch_rs1_master()
> vshard.storage.cfg(cfg, names.replica_uuid.box_2_b)
>
> fiber = require('fiber')
> -while not test_run:grep_log('box_2_a', "Run rebalancer") do fiber.sleep(0.1) end
> +while not test_run:grep_log('box_2_a', "Rebalancer has been started") do fiber.sleep(0.1) end
> while not test_run:grep_log('box_1_a', "Rebalancer location has changed") do fiber.sleep(0.1) end
>
> --
> diff --git a/test/router/reload.result b/test/router/reload.result
> index 19a9ead..47f3c2e 100644
> --- a/test/router/reload.result
> +++ b/test/router/reload.result
> @@ -116,10 +116,10 @@ vshard.router.module_version()
> check_reloaded()
> ---
> ...
> -while test_run:grep_log('router_1', 'Failover has been reloaded') == nil do fiber.sleep(0.1) end
> +while test_run:grep_log('router_1', 'Failover has been started') == nil do fiber.sleep(0.1) end
> ---
> ...
> -while test_run:grep_log('router_1', 'Discovery has been reloaded') == nil do fiber.sleep(0.1) vshard.router.discovery_wakeup() end
> +while test_run:grep_log('router_1', 'Discovery has been started') == nil do fiber.sleep(0.1) vshard.router.discovery_wakeup() end
> ---
> ...
> check_reloaded()
> diff --git a/test/router/reload.test.lua b/test/router/reload.test.lua
> index 6e21b74..af2939d 100644
> --- a/test/router/reload.test.lua
> +++ b/test/router/reload.test.lua
> @@ -59,8 +59,8 @@ vshard.router.module_version()
>
> check_reloaded()
>
> -while test_run:grep_log('router_1', 'Failover has been reloaded') == nil do fiber.sleep(0.1) end
> -while test_run:grep_log('router_1', 'Discovery has been reloaded') == nil do fiber.sleep(0.1) vshard.router.discovery_wakeup() end
> +while test_run:grep_log('router_1', 'Failover has been started') == nil do fiber.sleep(0.1) end
> +while test_run:grep_log('router_1', 'Discovery has been started') == nil do fiber.sleep(0.1) vshard.router.discovery_wakeup() end
>
> check_reloaded()
>
> diff --git a/test/storage/reload.result b/test/storage/reload.result
> index f689cf4..531d984 100644
> --- a/test/storage/reload.result
> +++ b/test/storage/reload.result
> @@ -113,13 +113,13 @@ vshard.storage.module_version()
> check_reloaded()
> ---
> ...
> -while test_run:grep_log('storage_2_a', 'Garbage collector has been reloaded') == nil do fiber.sleep(0.1) end
> +while test_run:grep_log('storage_2_a', 'Garbage collector has been started') == nil do fiber.sleep(0.1) end
> ---
> ...
> -while test_run:grep_log('storage_2_a', 'Recovery has been reloaded') == nil do fiber.sleep(0.1) vshard.storage.recovery_wakeup() end
> +while test_run:grep_log('storage_2_a', 'Recovery has been started') == nil do fiber.sleep(0.1) vshard.storage.recovery_wakeup() end
> ---
> ...
> -while test_run:grep_log('storage_2_a', 'Rebalancer has been reloaded') == nil do fiber.sleep(0.1) vshard.storage.rebalancer_wakeup() end
> +while test_run:grep_log('storage_2_a', 'Rebalancer has been started') == nil do fiber.sleep(0.1) vshard.storage.rebalancer_wakeup() end
> ---
> ...
> check_reloaded()
> diff --git a/test/storage/reload.test.lua b/test/storage/reload.test.lua
> index 6e19a92..64c3a60 100644
> --- a/test/storage/reload.test.lua
> +++ b/test/storage/reload.test.lua
> @@ -59,9 +59,9 @@ vshard.storage.module_version()
>
> check_reloaded()
>
> -while test_run:grep_log('storage_2_a', 'Garbage collector has been reloaded') == nil do fiber.sleep(0.1) end
> -while test_run:grep_log('storage_2_a', 'Recovery has been reloaded') == nil do fiber.sleep(0.1) vshard.storage.recovery_wakeup() end
> -while test_run:grep_log('storage_2_a', 'Rebalancer has been reloaded') == nil do fiber.sleep(0.1) vshard.storage.rebalancer_wakeup() end
> +while test_run:grep_log('storage_2_a', 'Garbage collector has been started') == nil do fiber.sleep(0.1) end
> +while test_run:grep_log('storage_2_a', 'Recovery has been started') == nil do fiber.sleep(0.1) vshard.storage.recovery_wakeup() end
> +while test_run:grep_log('storage_2_a', 'Rebalancer has been started') == nil do fiber.sleep(0.1) vshard.storage.rebalancer_wakeup() end
>
> check_reloaded()
>
> diff --git a/test/unit/util.result b/test/unit/util.result
> new file mode 100644
> index 0000000..a7b176d
> --- /dev/null
> +++ b/test/unit/util.result
> @@ -0,0 +1,72 @@
> +test_run = require('test_run').new()
> +---
> +...
> +fiber = require('fiber')
> +---
> +...
> +log = require('log')
> +---
> +...
> +test_util = require('util')
> +---
> +...
> +util = require('vshard.util')
> +---
> +...
> +test_run:cmd("setopt delimiter ';'")
> +---
> +- true
> +...
> +fake_M = {
> + reloadable_func = nil,
> + module_version = 1,
> +};
> +---
> +...
> +test_run:cmd("setopt delimiter ''");
> +---
> +- true
> +...
> +-- Check autoreload on function change during failure.
> +fake_M.reloadable_function = function () fake_M.reloadable_function = 42; error('Error happened.') end
> +---
> +...
> +fib = fiber.create(util.reloadable_fiber_f, fake_M, 'reloadable_function', 'Worker_name')
> +---
> +...
> +fib:cancel()
> +---
> +...
> +test_run:grep_log('default', 'Worker_name: reloadable function reloadable_function has been changed')
> +---
> +- 'Worker_name: reloadable function reloadable_function has been changed'
> +...
> +test_run:grep_log('default', 'Worker_name is reloaded, restarting')
> +---
> +- Worker_name is reloaded, restarting
> +...
> +test_run:grep_log('default', 'Worker_name has been started')
> +---
> +- Worker_name has been started
> +...
> +log.info(string.rep('a', 1000))
> +---
> +...
> +-- Check reload feature.
> +fake_M.reloadable_function = function () return true end
> +---
> +...
> +fib = fiber.create(util.reloadable_fiber_f, fake_M, 'reloadable_function', 'Worker_name')
> +---
> +...
> +fib:cancel()
> +---
> +...
> +test_run:grep_log('default', 'Worker_name is reloaded, restarting', 1000)
> +---
> +- Worker_name is reloaded, restarting
> +...
> +test_run:grep_log('default', 'Worker_name has been started', 1000)
> +---
> +- Worker_name has been started
> +...
> diff --git a/test/unit/util.test.lua b/test/unit/util.test.lua
> new file mode 100644
> index 0000000..9359378
> --- /dev/null
> +++ b/test/unit/util.test.lua
> @@ -0,0 +1,29 @@
> +test_run = require('test_run').new()
> +fiber = require('fiber')
> +log = require('log')
> +test_util = require('util')
> +util = require('vshard.util')
> +
> +test_run:cmd("setopt delimiter ';'")
> +fake_M = {
> + reloadable_func = nil,
> + module_version = 1,
> +};
> +test_run:cmd("setopt delimiter ''");
> +
> +-- Check autoreload on function change during failure.
> +fake_M.reloadable_function = function () fake_M.reloadable_function = 42; error('Error happened.') end
> +
> +fib = fiber.create(util.reloadable_fiber_f, fake_M, 'reloadable_function', 'Worker_name')
> +fib:cancel()
> +test_run:grep_log('default', 'Worker_name: reloadable function reloadable_function has been changed')
> +test_run:grep_log('default', 'Worker_name is reloaded, restarting')
> +test_run:grep_log('default', 'Worker_name has been started')
> +log.info(string.rep('a', 1000))
> +
> +-- Check reload feature.
> +fake_M.reloadable_function = function () return true end
> +fib = fiber.create(util.reloadable_fiber_f, fake_M, 'reloadable_function', 'Worker_name')
> +fib:cancel()
> +test_run:grep_log('default', 'Worker_name is reloaded, restarting', 1000)
> +test_run:grep_log('default', 'Worker_name has been started', 1000)
> diff --git a/vshard/router/init.lua b/vshard/router/init.lua
> index 21093e5..9e18b27 100644
> --- a/vshard/router/init.lua
> +++ b/vshard/router/init.lua
> @@ -491,11 +491,9 @@ local function router_cfg(cfg)
> end
> lreplicaset.wait_masters_connect(new_replicasets)
> if M.failover_fiber == nil then
> - log.info('Start failover fiber')
> lfiber.create(util.reloadable_fiber_f, M, 'failover_f', 'Failover')
> end
> if M.discovery_fiber == nil then
> - log.info('Start discovery fiber')
> lfiber.create(util.reloadable_fiber_f, M, 'discovery_f', 'Discovery')
> end
> -- Destroy connections, not used in a new configuration.
> diff --git a/vshard/storage/init.lua b/vshard/storage/init.lua
> index 57076e1..300751f 100644
> --- a/vshard/storage/init.lua
> +++ b/vshard/storage/init.lua
> @@ -692,10 +692,8 @@ local function local_on_master_enable()
> M.collect_bucket_garbage_fiber =
> lfiber.create(util.reloadable_fiber_f, M, 'collect_garbage_f',
> 'Garbage collector')
> - log.info("GC is started")
> M.recovery_fiber =
> lfiber.create(util.reloadable_fiber_f, M, 'recovery_f', 'Recovery')
> - log.info('Recovery is started')
> -- TODO: check current status
> log.info("Took on replicaset master role")
> end
> @@ -1585,7 +1583,6 @@ local function storage_cfg(cfg, this_replica_uuid)
>
> if min_master == this_replica then
> if not M.rebalancer_fiber then
> - log.info('Run rebalancer')
> M.rebalancer_fiber = lfiber.create(util.reloadable_fiber_f, M,
> 'rebalancer_f', 'Rebalancer')
> else
> diff --git a/vshard/util.lua b/vshard/util.lua
> index bb71318..ce79930 100644
> --- a/vshard/util.lua
> +++ b/vshard/util.lua
> @@ -2,6 +2,19 @@
> local log = require('log')
> local fiber = require('fiber')
>
> +local MODULE_INTERNALS = '__module_vshard_util'
> +local M = rawget(_G, MODULE_INTERNALS)
> +if not M then
> + --
> + -- The module is loaded for the first time.
> + --
> + M = {
> + -- Latest versions of functions.
> + reloadable_fiber_f = nil,
> + }
> + rawset(_G, MODULE_INTERNALS, M)
> +end
> +
> --
> -- Extract parts of a tuple.
> -- @param tuple Tuple to extract a key from.
> @@ -19,33 +32,42 @@ local function tuple_extract_key(tuple, parts)
> end
>
> --
> --- Wrapper to run @a func in infinite loop and restart it on the
> --- module reload. This function CAN NOT BE AUTORELOADED. To update
> --- it you must manualy stop all fibers, run by this function, do
> --- reload, and then restart all stopped fibers. This can be done,
> --- for example, by calling vshard.storage/router.cfg() again with
> --- the same config as earlier.
> +-- Wrapper to run a func in infinite loop and restart it on
> +-- errors and module reload.
> +-- To handle module reload and run new version of a function
> +-- in the module, the function should just return.
> --
> --- @param func Reloadable function to run. It must accept current
> --- module version as an argument, and interrupt itself,
> --- when it is changed.
> --- @param worker_name Name of the function. Usual infinite fiber
> --- represents a background subsystem, which has a name. For
> --- example: "Garbage Collector", "Recovery", "Discovery",
> --- "Rebalancer".
> --- @param M Module which can reload.
> +-- @param module Module which can be reloaded.
> +-- @param func_name Name of a function to be executed in the
> +-- module.
> +-- @param worker_name Name of the reloadable background subsystem.
> +-- For example: "Garbage Collector", "Recovery", "Discovery",
> +-- "Rebalancer". Used only for an activity logging.
> --
> -local function reloadable_fiber_f(M, func_name, worker_name)
> - while true do
> - local ok, err = pcall(M[func_name], M.module_version)
> - if not ok then
> - log.error('%s has been failed: %s', worker_name, err)
> - fiber.yield()
> - else
> - log.info('%s has been reloaded', worker_name)
> - fiber.yield()
> +local function reloadable_fiber_f(module, func_name, worker_name)
> + log.info('%s has been started', worker_name)
> + local func = module[func_name]
> +::reload_loop::
> + local ok, err = pcall(func, module.module_version)
> + -- yield serves two pursoses:
> + -- * makes this fiber cancellable
> + -- * prevents 100% cpu consumption
> + fiber.yield()
> + if not ok then
> + log.error('%s has been failed: %s', worker_name, err)
> + if func == module[func_name] then
> + goto reload_loop
> end
> + -- There is a chance that error was raised during reload
> + -- (or caused by reload). Perform reload in case function
> + -- has been changed.
> + log.error('%s: reloadable function %s has been changed',
> + worker_name, func_name)
> end
> + log.info('%s is reloaded, restarting', worker_name)
> + -- luajit drops this frame if next function is called in
> + -- return statement.
> + return M.reloadable_fiber_f(module, func_name, worker_name)
> end
>
> --
> @@ -75,8 +97,12 @@ local function generate_self_checker(obj_name, func_name, mt, func)
> end
> end
>
> +-- Update latest versions of function
> +M.reloadable_fiber_f = reloadable_fiber_f
> +
> return {
> tuple_extract_key = tuple_extract_key,
> reloadable_fiber_f = reloadable_fiber_f,
> generate_self_checker = generate_self_checker,
> + internal = M,
> }
>
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