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https://issues.apache.org/jira/browse/LIVY-735?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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runzhiwang updated LIVY-735:
Description:
Currently, the driver tries to support communicating with multi-clients, by
registering each client at
https://github.com/apache/incubator-livy/blob/master/rsc/src/main/java/org/apache/livy/rsc/driver/RSCDriver.java#L220.
But actually, if multi-clients connect to one driver, the rpc channel will
close, the reason are as follows.
1. In every communication, client sends two packages to driver: header\{type,
id}, and payload at
https://github.com/apache/incubator-livy/blob/master/rsc/src/main/java/org/apache/livy/rsc/rpc/RpcDispatcher.java#L144.
2. If client1 sends header1, payload1, and client2 sends header2, payload2 at
the same time.
The driver receives the package in the order: header1, header2, payload1,
payload2.
3. When driver receives header1, driver assigns lastHeader at
https://github.com/apache/incubator-livy/blob/master/rsc/src/main/java/org/apache/livy/rsc/rpc/RpcDispatcher.java#L73.
4. Then driver receives header2, driver process it as a payload at
https://github.com/apache/incubator-livy/blob/master/rsc/src/main/java/org/apache/livy/rsc/rpc/RpcDispatcher.java#L78
which cause exception and rpc channel closed.
In the muti-active HA mode, the design doc is at:
https://docs.google.com/document/d/1bD3qYZpw14_NuCcSGUOfqQ0pqvSbCQsOLFuZp26Ohjc/edit?usp=sharing,
the session is allocated among servers by consistent hashing. If a new livy
joins, some session will be migrated from old livy to new livy. If the session
client in new livy connect to driver before stoping session client in old livy,
then two session clients will both connect to driver, and rpc channel close. In
this case, it's hard to ensure only one client connect to one driver at any
time. So it's better to support multi-clients connect to one driver, which has
no side effects.
How to fix:
1. Move the code of processing client message from `RpcDispatcher` to each
`Rpc`.
2. Each `Rpc` registers itself to `channelRpc` in RpcDispatcher.
3. `RpcDispatcher` dispatches each message to `Rpc` according to
`ctx.channel()`.
> Fix RPC Channel Closed When Multi Clients Connect to One Driver
>
>
> Key: LIVY-735
> URL: https://issues.apache.org/jira/browse/LIVY-735
> Project: Livy
> Issue Type: Sub-task
>Reporter: Yiheng Wang
>Priority: Major
> Time Spent: 20m
> Remaining Estimate: 0h
>
> Currently, the driver tries to support communicating with multi-clients, by
> registering each client at
> https://github.com/apache/incubator-livy/blob/master/rsc/src/main/java/org/apache/livy/rsc/driver/RSCDriver.java#L220.
> But actually, if multi-clients connect to one driver, the rpc channel will
> close, the reason are as follows.
> 1. In every communication, client sends two packages to driver: header\{type,
> id}, and payload at
> https://github.com/apache/incubator-livy/blob/master/rsc/src/main/java/org/apache/livy/rsc/rpc/RpcDispatcher.java#L144.
> 2. If client1 sends header1, payload1, and client2 sends header2, payload2 at
> the same time.
> The driver receives the package in the order: header1, header2, payload1,
> payload2.
> 3. When driver receives header1, driver assigns lastHeader at
> https://github.com/apache/incubator-livy/blob/master/rsc/src/main/java/org/apache/livy/rsc/rpc/RpcDispatcher.java#L73.
> 4. Then driver receives header2, driver process it as a payload at
> https://github.com/apache/incubator-livy/blob/master/rsc/src/main/java/org/apache/livy/rsc/rpc/RpcDispatcher.java#L78
> which cause exception and rpc channel closed.
> In the muti-active HA mode, the design doc is at:
> https://docs.google.com/document/d/1bD3qYZpw14_NuCcSGUOfqQ0pqvSbCQsOLFuZp26Ohjc/edit?usp=sharing,
> the session is allocated among servers by consistent hashing. If a new livy
> joins, some session will be migrated from old livy to new livy. If the
> session client in new livy connect to driver before stoping session client in
> old livy, then two session clients will both connect to driver, and rpc
> channel close. In this case, it's hard to ensure only one client connect to
> one driver at any time. So it's better to support multi-clients connect to
> one driver, which has no side effects.
> How to fix:
> 1. Move the code of processing client message from `RpcDispatcher` to each
> `Rpc`.
> 2. Each `Rpc` registers itself to `channelRpc` in RpcDispatcher.
> 3. `RpcDispatcher` dispatches each message to `Rpc` according to
> `ctx.channel()`.
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