perf: set lower priority for background processes (frappe#21841)

frappe/utils/background_jobs.py

@@ -21,7 +21,7 @@
 import frappe
 import frappe.monitor
 from frappe import _
-from frappe.utils import cstr, get_bench_id
+from frappe.utils import cint, cstr, get_bench_id
 from frappe.utils.commands import log
 from frappe.utils.deprecations import deprecation_warning
 from frappe.utils.redis_queue import RedisQueue
@@ -268,6 +268,8 @@ def start_worker(
 	if os.environ.get("CI"):
 		setup_loghandlers("ERROR")
 
+	set_niceness()
+
 	logging_level = "INFO"
 	if quiet:
 		logging_level = "WARNING"
@@ -305,6 +307,7 @@ def start_worker_pool(
 	if os.environ.get("CI"):
 		setup_loghandlers("ERROR")
 
+	set_niceness()
 	logging_level = "INFO"
 	if quiet:
 		logging_level = "WARNING"
@@ -519,3 +522,24 @@ def get_job(job_id: str) -> Job:
 		return Job.fetch(create_job_id(job_id), connection=get_redis_conn())
 	except NoSuchJobError:
 		return None
+
+
+BACKGROUND_PROCESS_NICENESS = 10
+
+
+def set_niceness():
+	"""Background processes should have slightly lower priority than web processes.
+
+	Calling this function increments the niceness of process by configured value or default.
+	Note: This function should be called only once in process' lifetime.
+	"""
+
+	conf = frappe.get_conf()
+	nice_increment = BACKGROUND_PROCESS_NICENESS
+
+	configured_niceness = conf.get("background_process_niceness")
+
+	if configured_niceness is not None:
+		nice_increment = cint(configured_niceness)
+
+	os.nice(nice_increment)

frappe/utils/scheduler.py

@@ -16,7 +16,7 @@
 # imports - module imports
 import frappe
 from frappe.utils import cint, get_datetime, get_sites, now_datetime
-from frappe.utils.background_jobs import get_jobs
+from frappe.utils.background_jobs import set_niceness
 
 DATETIME_FORMAT = "%Y-%m-%d %H:%M:%S"
 
@@ -35,6 +35,7 @@ def start_scheduler() -> NoReturn:
 	Specify scheduler_interval in seconds in common_site_config.json"""
 
 	tick = cint(frappe.get_conf().scheduler_tick_interval) or 60
+	set_niceness()
 
 	while True:
 		time.sleep(tick)