import "github.com/cognusion/go-memoryguard"
Package memoryguard is a system to track the PSS memory usage of an os.Process and kill it if the usage exceeds the stated Limit.
const (
// LimitZeroError is returned by Limit(int64) when the passed variable is <= 0.
LimitZeroError = Error("please call Limit(int64) with a value greater than zero")
// LimitNilProcessError is returned by Limit(int64) when the referenced *os.Process is nil.
LimitNilProcessError = Error("a Process has not been created and assigned, or is nil")
// LimitOnceError is returned by Limit(int64) if it has been called without error previously.
LimitOnceError = Error("Limit(int64) already called once")
)type Error stringError is an error type
func (e Error) Error() stringError returns the stringified version of Error
type MemoryGuard struct {
// Name is a name to use in lieu of PID for messaging
Name string
// Interval is a time.Duration to wait between checking usage
Interval time.Duration
// DebugOut is a logger for debug information
DebugOut *log.Logger
// ErrOut is a logger for StdErr coming from a process
ErrOut *log.Logger
// KillChan will be closed if/when the process is killed
KillChan chan struct{}
// KillError will be any error returned by the "Kill" operation. Varies widely by OS. Usually nil.
KillError error
// StatsFrequency updates the internal frequency to which statistics are emitted to the debug logger. Default is 1 minute.
StatsFrequency time.Duration
// contains filtered or unexported fields
}MemoryGuard is our encapsulating mechanation, and should only be acquired via a New helper. Member functions are goro-safe, but all struct fields should be set immediatelyish after New(), and before Limit() is called.
// Get a handle on our process
us, _ := os.FindProcess(os.Getpid())
// Create a new MemoryGuard around the process
mg := New(us)
mg.Limit(512 * 1024 * 1024) // Set the HWM memory limit. You can change this at any time
// Do stuff that is memory-hungry
// Stop guarding. After this, if you want to guard the process again,
// Make a New() guard.
mg.Cancel()
// Cancel returns immediately, goros will end eventually.func New(Process *os.Process) *MemoryGuardNew takes an os.Process and returns a MemoryGuard for that process
func (m *MemoryGuard) Cancel()Cancel signals a Limit() operation to stop, returning immediately. After calling Cancel this MemoryGuard will be non-functional
func (*MemoryGuard) CancelWait
func (m *MemoryGuard) CancelWait()CancelWait signals a Limit() operation to stop, and waits to return until it is done. After calling CancelWait this MemoryGuard will be non-functional
// Get a handle on our process
us, _ := os.FindProcess(os.Getpid())
// Create a new MemoryGuard around the process
mg := New(us)
mg.Limit(512 * 1024 * 1024) // Set the HWM memory limit. You can change this at any time
// Do stuff that is memory-hungry
// Stop guarding. After this, if you want to guard the process again,
// Make a New() guard.
mg.CancelWait()
// CancelWait pauses until the goros are all done.func (m *MemoryGuard) Limit(max int64) errorLimit takes the max usage (in Bytes) for the process and acts on the PSS. Returns an error if Limit is called with a zero or negative value, with a nil Process reference (did you use New()?), or if it has already been called once before, successfully.
func (m *MemoryGuard) PSS() int64PSS returns the last known PSS value for the watched process, or the current value, if there was no last value. After a process is killed for going over, this will be the last value observed prior to process death.
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