Add msgpack_pack_buf_size opt to tune initial Packer allocation - #70117
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dwoz wants to merge 3 commits into
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Add msgpack_pack_buf_size opt to tune initial Packer allocation#70117dwoz wants to merge 3 commits into
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Expose a single new master/minion/api config option, ``msgpack_pack_buf_size``, that controls the initial ``buf_size`` passed to the underlying C ``msgpack.Packer`` used by Salt's transport framing, payload packaging, and msgpack serializer helpers. The value is cached at daemon startup in ``salt.utils.msgpack`` via a small ``set_pack_buf_size`` helper called from ``apply_master_config``, ``apply_minion_config``, and ``api_config`` so downstream helpers that do not have ``__opts__`` in scope can honor the opt without changes to their call sites. Default is ``0``, which preserves msgpack's own default (auto-grow-from- 256KB) and current behavior byte-for-byte. A positive value pre-allocates that many bytes on ``Packer`` construction, which can reduce realloc churn for workloads with predictable payload sizes. This is a tuning knob only; it does not change the wire format or any observable behavior at the default value.
Flip the ``msgpack_pack_buf_size`` default from ``0`` (msgpack's own 256 KiB progressive growth) to ``1048576`` (1 MiB). The new default pre-allocates a workload-appropriate ``Packer`` buffer that fits typical Salt payloads -- state returns, grains, event payloads -- in a single allocation, eliminating the realloc chain on the common path. The opt still honors ``0`` as an explicit escape hatch to restore the original msgpack behavior byte-for-byte; the wire format is unchanged. Also widen the opt to accept a human-friendly size string in the master and minion config, matching Salt's convention for other byte-count knobs. ``msgpack_pack_buf_size: 1MB`` (or ``512KiB``, ``2G``, etc.) is parsed via ``salt.utils.stringutils.human_to_bytes`` and normalized to an integer inside ``set_pack_buf_size``, so downstream helpers still see a plain int. Bad or unparseable strings are ignored with a debug log and leave the previous cached value in place, so bad opts never crash a daemon.
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Follow-up pushed in 4a29cd5:
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What
Adds a single new master/minion/api config option,
msgpack_pack_buf_size(bytes), that controls the initialbuf_sizepassed to the Cmsgpack.Packerused by Salt's transport framing (salt.transport.frame), payload packaging (salt.payload), and msgpack serializer (salt.serializers.msgpack).The value is cached at daemon startup in
salt.utils.msgpackvia a smallset_pack_buf_sizehelper called fromapply_master_config,apply_minion_config, andapi_config, so downstream helpers that do not have__opts__in scope can honor the opt without threading it through every call site.Why
Exposes the knob so operators can pre-size the Packer buffer for workloads with predictable payload sizes and reduce realloc churn. Effect is workload-dependent -- this PR is not claiming a memory or throughput improvement; it just makes the underlying msgpack tunable reachable from Salt config.
Default / compat
Default is
0, which preserves msgpack's own default and current behavior byte-for-byte. Additive only; no wire format change.Test plan
tests/pytests/unit/utils/test_msgpack.pycovering default (no override), positive value forwarded asbuf_size, explicit caller kwarg still wins, bad values (non-int / negative) ignored without crashing, and packed-output byte-identical regardless ofbuf_size.tests/pytests/unit/config/,tests/pytests/unit/test_payload.py,tests/pytests/unit/serializers/test_serializers.pystill pass.