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Malte Ubl
09118a3c25
scr_constrained_memory read /sys/fs/cgroup/memory.max, the root of the cgroup mount, and answered 0 for "max". Node's process.constrainedMemory() is libuv's uv_get_constrained_memory (libuv 1.51 in Node 24.15): the cgroup named by /proc/self/cgroup, the smaller of memory.max and memory.high (v2) or of memory.limit_in_bytes and memory.soft_limit_in_bytes (v1, falling back to the controller's root), with "max" and v1's page-aligned LONG_MAX read as UINT64_MAX and an unreadable file making the answer 0. The two only agreed inside a cgroup namespace; in a nested cgroup or a systemd scope the native build reported the root's limit (17179869184 in a 16 GB sandbox where Node answers 18446744073709552000, or 2147483648 under memory.high=2G), so programs that size themselves by it ran out of memory. process.availableMemory() follows uv_get_available_memory too: under a constraint no larger than the machine's memory, the constraint minus the cgroup's current usage; otherwise MemAvailable, then sysinfo's freeram. The corpus program prints the exact constraint, so Node and the native build must read the same cgroup.
16 lines
946 B
TypeScript
16 lines
946 B
TypeScript
// process.constrainedMemory() is libuv's uv_get_constrained_memory: on Linux
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// the smaller of memory.max and memory.high of the process's own cgroup
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// (named by /proc/self/cgroup), UINT64_MAX when both are "max", and 0 where
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// there is no cgroup; 0 elsewhere. It is printed exactly, so Node and the
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// native binary must read the same cgroup. availableMemory() changes with
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// usage, so only its bound is checked: under a constraint no larger than the
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// machine it is the constraint minus the cgroup's usage.
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import { totalmem } from "node:os";
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const constrained = process.constrainedMemory();
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console.log("constrained:", constrained);
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console.log("constrained is a number:", typeof constrained === "number" && constrained >= 0);
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const available = process.availableMemory();
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const bound = constrained > 0 && constrained <= totalmem() ? constrained : totalmem();
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console.log("available within bound:", available >= 0 && available <= bound);
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