Re: Creating index failed
The other problem which exists is; the case where two threads tries to create index with the same name with different index expression concurrently. I assume there are ways this could happen. One solution to address overall issue with index creation on partitioned region is by taking a distributed lock with the index name. When index creation request comes, it first acquires a distributed lock with the index name; any additional index creation with that name will be blocked till the previous index is created with the same name; during this time if the index creation comes through local or remote the exception can be ignored. As there is only one index creation will be in progress for the same request. -Anil. On 2/3/22, 4:41 AM, "Mario Kevo" wrote: Hi devs, After implementing ignoring exception some tests failed as we allowed now to pass command again (although it does nothing as the same index is already created by execution before). https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fapache%2Fgeode%2Fpull%2F7195data=04%7C01%7Cagingade%40vmware.com%7C5c8bc7454b9044a05b1308d9e71275dd%7Cb39138ca3cee4b4aa4d6cd83d9dd62f0%7C0%7C0%7C637794888745101984%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000sdata=wUnq5WuzXrRnpeq%2FM8Ah1vF3TL8tETKxd%2B35v%2FXUMLg%3Dreserved=0 There is a summary of how it works by now. When we are creating an index on a partitioned region, the locator sends to all members to create an index on all data it contains. The partitioned region is specific as it is normal that you want to index all data which are distributed on all members. That leads to every member will try to create it locally and send index create requests to all members on that site. All members will check if there is an already created index or index creating is in progress and wait for it. In case a remotely originated request comes but there is already created index it will respond with Index and send an acknowledgment to the request sender side. In case it is not created already it will create an index on that member and then respond to the request sender side. This behavior is okay if we are using a small number of the server or using the --member option while creating indexes(which has no sense to use on the partitioned region as already described down in the mail thread). The problem is when we are using a larger num of the servers(8 or more) or just with debugging on. It will slow down the whole process and then can happen that on some of the servers remotely originated create index request comes before locally request. In that case, a remotely originated request will see that there is no index with that name and will create a new one. But the problem happens after that when a local request comes and there is already created index it will think that it is from some execution before and throw IndexNameConflictException. https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fapache%2Fgeode%2Fblob%2Fdevelop%2Fgeode-core%2Fsrc%2Fmain%2Fjava%2Forg%2Fapache%2Fgeode%2Finternal%2Fcache%2FPartitionedRegion.java%23L8377data=04%7C01%7Cagingade%40vmware.com%7C5c8bc7454b9044a05b1308d9e71275dd%7Cb39138ca3cee4b4aa4d6cd83d9dd62f0%7C0%7C0%7C637794888745101984%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000sdata=0lbpsVQ63FjPaRBvhqmhmAsYp8V0gH3BokmbASBC9hg%3Dreserved=0 The create index command will fail(despite of that the index is created on all data, some with local requests ad some with remotely originated requests). There are two problems with this implementation: 1. The user doesn't know that the index is created and will try to create it again but then it will fail on all servers. 2. The cluster config is updated after the command is finished successfully, which is correct as we cannot update the cluster config before anything is done. The user can use indexes despite that command failed, but the problem is that after the restart it has nothing in the cluster config and will not create an index on them. So the question is what to do in this case? How to avoid this issue? Ignore exceptions and fix failing tests expect that a new create index command will pass or disable --member option if partition region is used(or just document it) and don't send a request on other members as the command will send to all members to create it. Or maybe something else? BR, Mario Šalje: Mario Kevo Poslano: 14. prosinca 2021. 14:06 Prima: dev@geode.apache.org Predmet: Odg: Creating index failed Hi Alexandar, The cluster config is updated at the end of the command execution, and only in case, the command is successful. I created PR with Anlikumar's suggestion, but some tests failed.
Odg: Creating index failed
Hi devs, After implementing ignoring exception some tests failed as we allowed now to pass command again (although it does nothing as the same index is already created by execution before). https://github.com/apache/geode/pull/7195 There is a summary of how it works by now. When we are creating an index on a partitioned region, the locator sends to all members to create an index on all data it contains. The partitioned region is specific as it is normal that you want to index all data which are distributed on all members. That leads to every member will try to create it locally and send index create requests to all members on that site. All members will check if there is an already created index or index creating is in progress and wait for it. In case a remotely originated request comes but there is already created index it will respond with Index and send an acknowledgment to the request sender side. In case it is not created already it will create an index on that member and then respond to the request sender side. This behavior is okay if we are using a small number of the server or using the --member option while creating indexes(which has no sense to use on the partitioned region as already described down in the mail thread). The problem is when we are using a larger num of the servers(8 or more) or just with debugging on. It will slow down the whole process and then can happen that on some of the servers remotely originated create index request comes before locally request. In that case, a remotely originated request will see that there is no index with that name and will create a new one. But the problem happens after that when a local request comes and there is already created index it will think that it is from some execution before and throw IndexNameConflictException. https://github.com/apache/geode/blob/develop/geode-core/src/main/java/org/apache/geode/internal/cache/PartitionedRegion.java#L8377 The create index command will fail(despite of that the index is created on all data, some with local requests ad some with remotely originated requests). There are two problems with this implementation: 1. The user doesn't know that the index is created and will try to create it again but then it will fail on all servers. 2. The cluster config is updated after the command is finished successfully, which is correct as we cannot update the cluster config before anything is done. The user can use indexes despite that command failed, but the problem is that after the restart it has nothing in the cluster config and will not create an index on them. So the question is what to do in this case? How to avoid this issue? Ignore exceptions and fix failing tests expect that a new create index command will pass or disable --member option if partition region is used(or just document it) and don't send a request on other members as the command will send to all members to create it. Or maybe something else? BR, Mario Šalje: Mario Kevo Poslano: 14. prosinca 2021. 14:06 Prima: dev@geode.apache.org Predmet: Odg: Creating index failed Hi Alexandar, The cluster config is updated at the end of the command execution, and only in case, the command is successful. I created PR with Anlikumar's suggestion, but some tests failed. https://github.com/apache/geode/pull/7195 I tried with ignoring exception if it is already created, but in that case, if run again the create index command with the same name and expression it will not fail. BR, Mario Šalje: Alexander Murmann Poslano: 7. prosinca 2021. 18:28 Prima: dev@geode.apache.org Predmet: Re: Creating index failed Hi Mario! I agree with you that the user wanted to index all the data in the region when using a partitioned region. But when the command is not successful, the cluster config is not updated. After the server restart, it will not have indexes as it is not stored in the cluster configuration. Interesting! If I understand you correctly, the initial request to each server succeeds, but later ones will fail because the index is already there. However, the first, successful request should also have updated the cluster config, right?. Am I misunderstanding something? From: Mario Kevo Sent: Tuesday, December 7, 2021 06:36 To: dev@geode.apache.org Subject: Odg: Creating index failed Hi Jason, I agree with you that the user wanted to index all the data in the region when using a partitioned region. But when the command is not successful, the cluster config is not updated. After the server restart, it will not have indexes as it is not stored in the cluster configuration. So there should be some changes, as the index is created on all members but the command is not successful. I'm working on a fix. As soon as possible I will create PR on the already mentioned ticket. BR, Mario
