uWSGI懶惰的應用程序和線程池

Question

與

$ cat /etc/uwsgi/uwsgi.cfg 

[uwsgi] 
callable = app 
socket = /var/run/arivale-service/uwsgi.sock 
chmod-socket = 666 
pidfile = /var/run/arivale-service/uwsgi.pid 
master = true 
enable-threads = true 
single-interpreter = true 
thunder-lock 
need-app 
processes = 4 

運行uWSGI沒有lazy-apps啓用，給調用的請求下端點掛起

import boto3 
# ...irrelevant imports 
from multiprocessing.dummy import Pool as ThreadPool 


POOL = ThreadPool(6) 

# ...irrelevant setup 


def get_ecs_task_definitions(service_name): 
    ecs_service_name, _ = get_ecs_service_name_and_cluster(service_name) 

    def get_task_definition(task_definition_arn): 
     formatted_task_definition = {} 
     task_definition = ECS.describe_task_definition(taskDefinition=task_definition_arn)['taskDefinition'] 
     # ... 
     # build formatted_task_definition from task_definition 
     # ... 
     return formatted_task_definition 
    task_definition_arns = ECS.list_task_definitions(
     familyPrefix=ecs_service_name, status='ACTIVE')['taskDefinitionArns'] 
    return POOL.map(get_task_definition, task_definition_arns) 


@service.api('/api/services/<service_name>/ecs/task-definitions') 
def get_task_definitions(service_name): 
    return {'service_name': service_name, 'task_definitions': get_ecs_task_definitions(service_name)} 

它說什麼

NGINX是平衡uWSGI的應用程序，這是在error.log（NGINX）：

Jun 10 03:54:26 93e04e04e2cf nginx_error: 2017/06/10 03:54:26 [error] 49#49: *33 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 172.16.254.95, server: localhost, request: "GET /api/services/data-analysis-service/ecs/task-definitions HTTP/1.1",upstream: "uwsgi://unix:/var/run/arivale-service/uwsgi.sock", host: "devops-service.arivale.com"

每個請求到端點掛工人（下面是uwsgitop後2請求的輸出）：

uwsgi-2.0.15 - Sat Jun 10 21:26:10 2017 - req: 0 - RPS: 0 - lq: 0 - tx: 0 
node: localhost - cwd: /var/www/arivale-service/web - uid: 0 - gid: 0 - masterpid: 45 
WID %  PID  REQ  RPS  EXC  SIG  STATUS AVG  RSS  VSZ  TX  ReSpwn HC  RunT LastSpwn 
1  0.0  74  0  0  0  0  busy 0ms  0  0  0  1  0  0  21:23:20 
2  0.0  75  0  0  0  0  busy 0ms  0  0  0  1  0  0  21:23:20 
3  0.0  76  0  0  0  0  idle 0ms  0  0  0  1  0  0  21:23:20 
4  0.0  77  0  0  0  0  idle 0ms  0  0  0  1  0  0  21:23:20 

啓用lazy-apps修復該問題。有誰肯定地知道爲什麼？

Answer 1

發生這種情況是因爲uWSGI工作人員無法訪問在主服務器中創建的線程池，請參閱https://stackoverflow.com/a/39890941/2419669。

使用@postfork修復了這個：

global THREAD_POOL = None 

@postfork 
def _make_thread_pool(): 
    global THREAD_POOL 
    THREAD_POOL = ThreadPool(8)