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https://issues.apache.org/jira/browse/HDFS-17302?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Jian Zhang updated HDFS-17302:
------------------------------
Description:
[HDFS-14090|https://issues.apache.org/jira/browse/HDFS-14090] provides a
StaticRouterRpcFairnessPolicyController to support configuring different
handlers for different ns. Using the StaticRouterRpcFairnessPolicyController
allows the router to isolate different ns, and the ns with a higher load will
not affect the router's access to the ns with a normal load. But the
StaticRouterRpcFairnessPolicyController still falls short in many ways, such as:
1. *Configuration is inconvenient and error-prone*: When I use
StaticRouterRpcFairnessPolicyController, I first need to know how many handlers
the router has in total, then I have to know how many nameservices the router
currently has, and then carefully calculate how many handlers to allocate to
each ns so that the sum of handlers for all ns will not exceed the total
handlers of the router, and I also need to consider how many handlers to
allocate to each ns to achieve better performance. Therefore, I need to be very
careful when configuring. Even if I configure only one more handler for a
certain ns, the total number is more than the number of handlers owned by the
router, which will also cause the router to fail to start. At this time, I had
to investigate the reason why the router failed to start. After finding the
reason, I had to reconsider the number of handlers for each ns.
2. *Extension ns is not supported*: During the running of the router, if a new
ns is added to the cluster and a mount is added for the ns, but because no
handler is allocated for the ns, the ns cannot be accessed through the router.
We must reconfigure the number of handlers and then refresh the configuration.
At this time, the router can access the ns normally. When we reconfigure the
number of handlers, we have to face disadvantage 1: Configuration is
inconvenient and error-prone.
3. *Cannot share handlers*: The main purpose of proposing
RouterRpcFairnessPolicyController is to enable the router to access ns with
normal load and not be affected by ns with higher load. First of all, not all
ns have high loads; secondly, ns with high loads do not have high loads 24
hours a day. It may be that only certain time periods, such as 0 to 8 o'clock,
have high loads, and other time periods have normal loads. Assume there are 2
ns, and each ns is allocated half of the number of handlers. Assume that ns1
has many requests from 0 o'clock to 14 o'clock, and almost no requests from 14
o'clock to 24 o'clock. ns2 has many requests from 12 o'clock to 24 o'clock, and
0 o'clock - There are almost no requests at 12 o'clock; when it is between 0
o'clock and 12 o'clock and between 14 o'clock and 24 o'clock, only one ns has
more requests and the other ns has almost no requests, so we have wasted half
of the number of handlers.
was:
[HDFS-14090|https://issues.apache.org/jira/browse/HDFS-14090] provides a
StaticRouterRpcFairnessPolicyController to support configuring different
handlers for different ns. Using the StaticRouterRpcFairnessPolicyController
allows the router to isolate different ns, and the ns with a higher load will
not affect the router's access to the ns with a normal load. But the
StaticRouterRpcFairnessPolicyController still falls short in many ways, such as:
1. *Configuration is inconvenient and error-prone*: When I use
StaticRouterRpcFairnessPolicyController, I first need to know how many handlers
the router has in total, then I have to know how many nameservices the router
currently has, and then carefully calculate how many handlers to allocate to
each ns so that the sum of handlers for all ns will not exceed the total
handlers of the router, and I also need to consider how many handlers to
allocate to each ns to achieve better performance. Therefore, I need to be very
careful when configuring. Even if I configure only one more handler for a
certain ns, the total number is more than the number of hadnlers owned by the
router, which will also cause the router to fail to start. At this time, I had
to investigate the reason why the router failed to start. After finding the
reason, I had to reconsider the number of handlers for each ns.
2. *Extension ns is not supported*: During the running of the router, if a new
ns is added to the cluster and a mount is added for the ns, but because no
handler is allocated for the ns, the ns cannot be accessed through the router.
We must reconfigure the number of handlers and then refresh the configuration.
At this time, the router can access the ns normally. When we reconfigure the
number of handlers, we have to face disadvantage 1: Configuration is
inconvenient and error-prone.
3. *Cannot share handlers*:
> RBF: ProportionRouterRpcFairnessPolicyController-support proportional
> allocation of semaphores
> ----------------------------------------------------------------------------------------------
>
> Key: HDFS-17302
> URL: https://issues.apache.org/jira/browse/HDFS-17302
> Project: Hadoop HDFS
> Issue Type: New Feature
> Components: rbf
> Reporter: Jian Zhang
> Assignee: Jian Zhang
> Priority: Major
> Labels: pull-request-available
> Attachments: HDFS-17302.001.patch, HDFS-17302.002.patch
>
>
> [HDFS-14090|https://issues.apache.org/jira/browse/HDFS-14090] provides a
> StaticRouterRpcFairnessPolicyController to support configuring different
> handlers for different ns. Using the StaticRouterRpcFairnessPolicyController
> allows the router to isolate different ns, and the ns with a higher load will
> not affect the router's access to the ns with a normal load. But the
> StaticRouterRpcFairnessPolicyController still falls short in many ways, such
> as:
> 1. *Configuration is inconvenient and error-prone*: When I use
> StaticRouterRpcFairnessPolicyController, I first need to know how many
> handlers the router has in total, then I have to know how many nameservices
> the router currently has, and then carefully calculate how many handlers to
> allocate to each ns so that the sum of handlers for all ns will not exceed
> the total handlers of the router, and I also need to consider how many
> handlers to allocate to each ns to achieve better performance. Therefore, I
> need to be very careful when configuring. Even if I configure only one more
> handler for a certain ns, the total number is more than the number of
> handlers owned by the router, which will also cause the router to fail to
> start. At this time, I had to investigate the reason why the router failed to
> start. After finding the reason, I had to reconsider the number of handlers
> for each ns.
> 2. *Extension ns is not supported*: During the running of the router, if a
> new ns is added to the cluster and a mount is added for the ns, but because
> no handler is allocated for the ns, the ns cannot be accessed through the
> router. We must reconfigure the number of handlers and then refresh the
> configuration. At this time, the router can access the ns normally. When we
> reconfigure the number of handlers, we have to face disadvantage 1:
> Configuration is inconvenient and error-prone.
> 3. *Cannot share handlers*: The main purpose of proposing
> RouterRpcFairnessPolicyController is to enable the router to access ns with
> normal load and not be affected by ns with higher load. First of all, not all
> ns have high loads; secondly, ns with high loads do not have high loads 24
> hours a day. It may be that only certain time periods, such as 0 to 8
> o'clock, have high loads, and other time periods have normal loads. Assume
> there are 2 ns, and each ns is allocated half of the number of handlers.
> Assume that ns1 has many requests from 0 o'clock to 14 o'clock, and almost no
> requests from 14 o'clock to 24 o'clock. ns2 has many requests from 12 o'clock
> to 24 o'clock, and 0 o'clock - There are almost no requests at 12 o'clock;
> when it is between 0 o'clock and 12 o'clock and between 14 o'clock and 24
> o'clock, only one ns has more requests and the other ns has almost no
> requests, so we have wasted half of the number of handlers.
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