gripleaf opened a new issue, #240: URL: https://github.com/apache/paimon-cpp/issues/240
### Search before asking - [x] I searched in the [issues](https://github.com/apache/paimon-cpp/issues) and found nothing similar. ### Motivation Recent profiling of highly concurrent scans has revealed several performance bottlenecks caused by repeated operations on Arrow-returned `shared_ptr` objects in hot read loops. Two significant cases have been identified: 1. Manifest readers repeatedly call `StructArray::fields()` while processing individual rows. This copies `shared_ptr<Array>` objects and, with GCC 8.3's libstdc++, can introduce substantial lock contention through `_Sp_locker`, `pthread_mutex_lock`, and futex waits when multiple workers read manifests concurrently. 2. Avro decoding calls `ArrayBuilder::type()` for every integer and timestamp value. Because this method returns `std::shared_ptr<DataType>` by value, concurrent scans repeatedly modify reference counts on shared Arrow primitive data types, causing cache-line contention. Profiling showed `ArrayBuilder::type()` and shared-pointer release operations accounting for a large proportion of samples after the manifest bottleneck was removed. This issue tracks the broader effort to identify and eliminate similar shared-pointer operations from scan hot paths. The goal is to cache immutable Arrow metadata at an appropriate batch, reader, or builder lifetime, while ensuring caches are invalidated whenever the corresponding Arrow object tree is replaced. The expected outcome is lower synchronization and reference-counting overhead under concurrent scans, allowing CPU time to return to actual decoding, memory copying, and buffer management. ### Solution _No response_ ### Anything else? _No response_ ### Are you willing to submit a PR? - [ ] I'm willing to submit a PR! -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
