74 lines
2.1 KiB
Go
74 lines
2.1 KiB
Go
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package watchdog
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import (
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"fmt"
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"os"
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"time"
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"github.com/containerd/cgroups"
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)
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var (
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pid = os.Getpid()
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memSubsystem = cgroups.SingleSubsystem(cgroups.V1, cgroups.Memory)
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)
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// CgroupDriven initializes a cgroups-driven watchdog. It will try to discover
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// the memory limit from the cgroup of the process (derived from /proc/self/cgroup),
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// or from the root cgroup path if the PID == 1 (which indicates that the process
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// is running in a container).
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//
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// Memory usage is calculated by querying the cgroup stats.
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//
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// This function will return an error immediately if the OS does not support cgroups,
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// or if another error occurs during initialization. The caller can then safely fall
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// back to the system driven watchdog.
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func CgroupDriven(frequency time.Duration, policyCtor PolicyCtor) (err error, stopFn func()) {
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// use self path unless our PID is 1, in which case we're running inside
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// a container and our limits are in the root path.
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path := cgroups.NestedPath("")
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if pid := os.Getpid(); pid == 1 {
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path = cgroups.RootPath
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}
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cgroup, err := cgroups.Load(memSubsystem, path)
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if err != nil {
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return fmt.Errorf("failed to load cgroup for process: %w", err), nil
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}
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var limit uint64
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if stat, err := cgroup.Stat(); err != nil {
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return fmt.Errorf("failed to load memory cgroup stats: %w", err), nil
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} else if stat.Memory == nil || stat.Memory.Usage == nil {
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return fmt.Errorf("cgroup memory stats are nil; aborting"), nil
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} else {
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limit = stat.Memory.Usage.Limit
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}
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if limit == 0 {
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return fmt.Errorf("cgroup limit is 0; refusing to start memory watchdog"), nil
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}
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policy, err := policyCtor(limit)
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if err != nil {
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return fmt.Errorf("failed to construct policy with limit %d: %w", limit, err), nil
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}
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if err := start(UtilizationProcess); err != nil {
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return err, nil
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}
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_watchdog.wg.Add(1)
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go pollingWatchdog(policy, frequency, limit, func() (uint64, error) {
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stat, err := cgroup.Stat()
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if err != nil {
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return 0, err
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} else if stat.Memory == nil || stat.Memory.Usage == nil {
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return 0, fmt.Errorf("cgroup memory stats are nil; aborting")
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}
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return stat.Memory.Usage.Usage, nil
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})
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return nil, stop
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}
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