Make Bazel's RAM estimate container aware #20435
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As of JDK 14, `OperatingSystemMXBean` provides information about system memory that is container-aware. Outside containers, it uses the same mechanisms as Bazel to determine available RAM (`/proc/meminfo` on Linux, `hw.memsize` on macOS) and can thus be used as a drop-in replacement for the custom implementation. A small caveat is that Bazel's macOS RAM estimate was based on converting bytes to "MB" via a divisor of `1000^2` instead of `1024^2`, resulting in a consistent overestimate compared to an identical Linux machine that is now corrected. This opportunity was missed in bazelbuild#16512 since `OperatingSystemMXBean` is based on a complete Java implementation of cgroups handling and doesn't go through the `os::total_memory` or `os::physical_memory` Hotspot functions. RELNOTES[INC]: * On Linux, Bazel's RAM estimate for the host machine is now aware of container resource limits. * On macOS, Bazel no longer consistently overestimates the total RAM by ~5% (`1024^2/1000^2`). * On Windows, Bazel's RAM estimate is now generally more accurate as it is no longer influenced by JVM heuristics. Fixes bazelbuild#3886 Closes bazelbuild#20435. PiperOrigin-RevId: 588718034 Change-Id: I2daafa0567740a1b149ca8756ec27f102129283c
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As of JDK 14, `OperatingSystemMXBean` provides information about system memory that is container-aware. Outside containers, it uses the same mechanisms as Bazel to determine available RAM (`/proc/meminfo` on Linux, `hw.memsize` on macOS) and can thus be used as a drop-in replacement for the custom implementation. A small caveat is that Bazel's macOS RAM estimate was based on converting bytes to "MB" via a divisor of `1000^2` instead of `1024^2`, resulting in a consistent overestimate compared to an identical Linux machine that is now corrected. This opportunity was missed in #16512 since `OperatingSystemMXBean` is based on a complete Java implementation of cgroups handling and doesn't go through the `os::total_memory` or `os::physical_memory` Hotspot functions. RELNOTES[INC]: * On Linux, Bazel's RAM estimate for the host machine is now aware of container resource limits. * On macOS, Bazel no longer consistently overestimates the total RAM by ~5% (`1024^2/1000^2`). * On Windows, Bazel's RAM estimate is now generally more accurate as it is no longer influenced by JVM heuristics. Fixes #3886 Closes #20435. Commit 2f3cdc5 PiperOrigin-RevId: 588718034 Change-Id: I2daafa0567740a1b149ca8756ec27f102129283c Co-authored-by: Fabian Meumertzheim <[email protected]>
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As of JDK 14, `OperatingSystemMXBean` provides information about system memory that is container-aware. Outside containers, it uses the same mechanisms as Bazel to determine available RAM (`/proc/meminfo` on Linux, `hw.memsize` on macOS) and can thus be used as a drop-in replacement for the custom implementation. A small caveat is that Bazel's macOS RAM estimate was based on converting bytes to "MB" via a divisor of `1000^2` instead of `1024^2`, resulting in a consistent overestimate compared to an identical Linux machine that is now corrected. This opportunity was missed in bazelbuild#16512 since `OperatingSystemMXBean` is based on a complete Java implementation of cgroups handling and doesn't go through the `os::total_memory` or `os::physical_memory` Hotspot functions. RELNOTES[INC]: * On Linux, Bazel's RAM estimate for the host machine is now aware of container resource limits. * On macOS, Bazel no longer consistently overestimates the total RAM by ~5% (`1024^2/1000^2`). * On Windows, Bazel's RAM estimate is now generally more accurate as it is no longer influenced by JVM heuristics. Fixes bazelbuild#3886 Closes bazelbuild#20435. PiperOrigin-RevId: 588718034 Change-Id: I2daafa0567740a1b149ca8756ec27f102129283c
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As of JDK 14,
OperatingSystemMXBeanprovides information about system memory that is container-aware. Outside containers, it uses the same mechanisms as Bazel to determine available RAM (/proc/meminfoon Linux,hw.memsizeon macOS) and can thus be used as a drop-in replacement for the custom implementation.A small caveat is that Bazel's macOS RAM estimate was based on converting bytes to "MB" via a divisor of
1000^2instead of1024^2, resulting in a consistent overestimate compared to an identical Linux machine that is now corrected.This opportunity was missed in #16512 since
OperatingSystemMXBeanis based on a complete Java implementation of cgroups handling and doesn't go through theos::total_memoryoros::physical_memoryHotspot functions.RELNOTES[INC]:
1024^2/1000^2).Fixes #3886