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Configuration

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This page covers go-scheduler's scheduler settings, per-task options, and the runtime defaults for logging and the worker pool.

Scheduler Settings

type Config struct {
    Location *time.Location
}
Field Default Effect
Location time.Local Timezone used to compute the next fire time of cron expressions and descriptors 
loc, err := time.LoadLocation("Asia/Taipei")
if err != nil {
    log.Fatal(err)
}

c, err := core.New(core.Config{Location: loc})
if err != nil {
    log.Fatal(err)
}

if _, err := c.Add("30 9 * * 1-5", func() error {
    return sendReport()
}, "weekday report"); err != nil {
    log.Fatal(err)
}

30 9 * * 1-5 fires at 09:30 Monday to Friday in Asia/Taipei time.

The package reads no environment variables or configuration files.

Task Options

Add identifies variadic arguments by type, in any order:

func (c *cron) Add(spec string, action interface{}, arg ...interface{}) (int64, error)
Type Sets Notes
string Task description Logged by the dependency worker
time.Duration Execution limit Not a start delay; 0 means no limit
func() Timeout callback Called only when the execution limit is exceeded
[]core.Wait Prerequisites Action must be func() error
[]int64 Prerequisites (deprecated) Each ID becomes Wait{ID: id} with the Stop policy

When the same type is passed more than once, the last string / time.Duration / func() wins, while []core.Wait and []int64 accumulate.

_, err := c.Add("*/10 * * * *", func() error {
    return syncInventory()
}, "inventory sync", 2*time.Minute, func() {
    log.Println("inventory sync exceeded 2m")
}, []core.Wait{
    {ID: authID, State: core.Stop},
    {ID: cacheID, State: core.Skip},
})
if err != nil {
    log.Fatal(err)
}

Dependency Settings

Field Value Effect
ID Prerequisite task ID Dependent task fails when the ID does not exist
State core.Stop (default) Dependent task fails when the prerequisite fails
State core.Skip Failed prerequisite is ignored
Delay Any Currently not applied; the wait limit is fixed at 1 minute

Runtime Defaults

Item Value Source
Logger syslog (LOG_INFO|LOG_LOCAL0, tag goCron) in JSON core/instance.go
Logger fallback stderr text, Info level When syslog cannot be opened
Dependency workers runtime.NumCPU(), or 2 when CPUs ≤ 2 core/depend.go
Wait queue capacity 1024 core/depend.go
Dependency poll interval 1ms core/dependManager.go
@every minimum interval 30 seconds core/schedule.go

None of these values can be changed by callers.

See Task Dependencies and Timeouts for runtime behavior.

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