[IMPALA-12681] Some local file descriptors not released when using remote spilling

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Impala 4.0.0, Impala 4.1.0, Impala 4.2.0, Impala 4.3.0
• Fix Version/s: Impala 4.4.0
• Component/s: Backend
• Epic Link: Spill to S3 Support
• Target Version: Impala 4.4.0
• Epic Color: ghx-label-14
• Assignee: Yida Wu
• Reporter: Yida Wu
• Created: 04/Jan/24 06:28
• Updated: 07/Feb/24 09:44
• Resolved: 09/Jan/24 00:20

Description

The bug occurs during remote spilling when writing spilled data to local buffers. In this process, if the files are not completely filled, such as when no more data is incoming at the end of spilling, there is a possibility of partial writes to the files, the files might be physically removed without properly releasing the associated file descriptor. This issue can be observed in cases like the one described below.

find /proc/*/fd -ls | grep '(deleted)'
288574785 0 lrwx------ 1 impala impala 64 Jan 3 14:24 /proc/x/fd/xxxx -> /opt/impala/scratch/impala-scratch/impala-scratch-xxxxxxxxx-xxxx-xxxx\ (deleted) 

In such a scenario, the disk space occupied by the file may not be reclaimed because the file descriptor still maintains a reference to the file.