fix(ActiveQueryTracker): avoid SIGBUS by explicitly allocating active query log file#433
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u-veles-a wants to merge 7 commits into
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fix(ActiveQueryTracker): avoid SIGBUS by explicitly allocating active query log file#433u-veles-a wants to merge 7 commits into
u-veles-a wants to merge 7 commits into
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… query log file Signed-off-by: Alexandr Yudin <57181751+u-veles-a@users.noreply.github.com>
Signed-off-by: Alexandr Yudin <57181751+u-veles-a@users.noreply.github.com>
vporoshok
approved these changes
Jul 23, 2026
vporoshok
enabled auto-merge (squash)
July 23, 2026 07:27
Signed-off-by: Alexandr Yudin <57181751+u-veles-a@users.noreply.github.com>
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Description
The active query tracker uses a memory-mapped queries.active file. Previously, the file was sized with file.Truncate, which can create a sparse file on some filesystems. In that case, the operating system may accept the file size change without physically allocating the required disk space. If the disk later becomes full and Prometheus tries to write to it, the write can fail with SIGBUS.
This change, preallocates the active query tracker file by writing zeroes to it and syncing it before the file is memory-mapped. This makes the failure mode explicit and recoverable during startup or initialization.
The code is copied from the upstream.