from concurrent.futures import ThreadPoolExecutor
from tornado.ioloop import IOLoop
from tornado.concurrent import run_on_executor
import contextvars
ctx_var = contextvars.ContextVar("ctx_var")

class SleepHandler(tornado.web.RequestHandler):


    executor = ThreadPoolExecutor(10)


    @tornado.gen.coroutine
    def get(self):
        start = time.time()
        ctx_var.set('xxx')
        //how can i pass ctx_var to sleep
        res = yield self.sleep()
        self.write("when i sleep %f s" % (time.time() - start))
        self.finish()

    @run_on_executor
    def sleep(self):
        //here i want "ctx_var.get()"
        time.sleep(5)
        return 5

    @tornado.gen.coroutine
    def get(self):
        start = time.time()
        ctx_var.set('xxx')
        ctx = contextvars.copy_context()
        res = yield IOLoop.current().run_in_executor(None, ctx.run, self.sleep)
        self.write("when i sleep %f s" % (time.time() - start))
        self.finish()