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https://issues.apache.org/jira/browse/RATIS-97?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16105361#comment-16105361
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Tsz Wo Nicholas Sze edited comment on RATIS-97 at 7/31/17 9:20 PM:
-------------------------------------------------------------------
> ... a new leader needs to get majority from both the old configuration and
> the new configuration, ...
But how would the new servers know about the old configuration in the first
place? Currently, we just start new servers with one configuration.
> Do you have a test case for this scenario, Nicholas?
Yes, I discovered this bug from RATIS-96. With the patch there, we can easily
modify testReinitialize9Nodes. Then run it with Grpc repeatedly. It should
fail within a few times.
{code}
diff --git
a/ratis-server/src/test/java/org/apache/ratis/server/impl/ReinitializationBaseTest.java
b/ratis-server/src/test/java/org/apache/ratis/server/impl/ReinitializationBaseTest.java
index 20b8680..f4ce320 100644
---
a/ratis-server/src/test/java/org/apache/ratis/server/impl/ReinitializationBaseTest.java
+++
b/ratis-server/src/test/java/org/apache/ratis/server/impl/ReinitializationBaseTest.java
@@ -106,7 +106,7 @@ public abstract class ReinitializationBaseTest {
@Test
public void testReinitialize9Nodes() throws Exception {
final int[] idIndex = {5, 8, 9};
- runTestReinitializeMultiGroups(idIndex, 0);
+ runTestReinitializeMultiGroups(idIndex, 2);
}
private void runTestReinitializeMultiGroups(int[] idIndex, int chosen)
throws Exception {
{code}
was (Author: szetszwo):
> ... a new leader needs to get majority from both the old configuration and
> the new configuration, ...
But how would the new servers know about the old configuration in the first
place? Currently, we just start new servers with one configuration.
> Do you have a test case for this scenario, Nicholas?
Yes, I discovered this bug from RATIS-96. With the patch there, we can easily
add a test.
{code}
@Test
public void testReinitialize9Nodes() throws Exception {
final int[] idIndex = {3, 9};
runTestReinitializeMultiGroups(idIndex, 0);
}
{code}
> Leader may not have majority after setConfiguration
> ---------------------------------------------------
>
> Key: RATIS-97
> URL: https://issues.apache.org/jira/browse/RATIS-97
> Project: Ratis
> Issue Type: Bug
> Reporter: Tsz Wo Nicholas Sze
> Assignee: Tsz Wo Nicholas Sze
> Attachments: r97_20170728.patch
>
>
> Here is an example: Suppose a group has 3 servers and one of them is the
> leader. Use setConfiguration to add 6 more servers. The leader is still
> running as a leader although it does not has majority anymore. The 6 new
> servers may elect a new leader among them. Finally, there are two leaders in
> the group.
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