shell-sched is a simple concurrent task scheduler based on shell and few GNU tools.

Features

• Concurrent and asynchronous
• Priority based schedule
• Dynamic tuning and slow start
• Less intrusion

Important

The scheduler can only be enabled when SCHED_ENABLED=1 (default).

If not, all task emited run serially as normal rather than exit with error.

Usage example

If you want sleep 10 seconds in background:

# Import all things of sched.sh into current shell proccess.
source sched.sh 

# Startup scheduler
sched::startup

# Emit a task to scheduler
sched::emit "sleep 10"

# Block current proccess for waiting tasks. Optional, if absent, tasks have still be running in background
sched::wait_all_tasks

# Shutdown scheduler
sched::shutdown

Exposed environment variables

1. SCHED_ENABLED

   Enable or disable scheduler

   1 -> enable, 0 -> disable

2. SCHED_DATA_ROOT

   Root path that stored intermediate data on runtime. Default is under /tmp that is generated automaticlly by runtime.

3. SCHED_MAX_RUNNERS

   Max parrallel task counts. Must be great than 0. Default (2 * cpu cores)

4. SCHED_DEBUG

   Enable or disable scheduler debug log

   1 -> enable, 0 -> disable

Exposed functions show as below:

1. sched::startup

   Start scheduler

2. sched::shutdown

   Stop scheduler

3. sched::emit <task> [<priority>]

   Emit a task to scheduler which would select a task to execute asynchronously based on its priority

   Note: task must be a function or one-line command

4. sched::wait_all_tasks_and_exit

   Wait all tasks complete or any error occurred, and exit the calling proceess

5. sched::wait_all_tasks

   Wait all tasks complete or any error occurred, only exit the calling proccess when error occurred