From 54a4e1b53a18f0c7420ba03de9608194c4413fc2 Mon Sep 17 00:00:00 2001 From: Raymond Hettinger Date: Sun, 17 Oct 2021 18:20:34 -0500 Subject: Improve multiserver queue recipe (GH-29012) --- Doc/library/random.rst | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/Doc/library/random.rst b/Doc/library/random.rst index 0ac0fe7..36f232d 100644 --- a/Doc/library/random.rst +++ b/Doc/library/random.rst @@ -503,7 +503,7 @@ between the effects of a drug versus a placebo:: Simulation of arrival times and service deliveries for a multiserver queue:: - from heapq import heappush, heappop + from heapq import heapify, heapreplace from random import expovariate, gauss from statistics import mean, quantiles @@ -515,14 +515,15 @@ Simulation of arrival times and service deliveries for a multiserver queue:: waits = [] arrival_time = 0.0 servers = [0.0] * num_servers # time when each server becomes available - for i in range(100_000): + heapify(servers) + for i in range(1_000_000): arrival_time += expovariate(1.0 / average_arrival_interval) - next_server_available = heappop(servers) + next_server_available = servers[0] wait = max(0.0, next_server_available - arrival_time) waits.append(wait) - service_duration = gauss(average_service_time, stdev_service_time) + service_duration = max(0.0, gauss(average_service_time, stdev_service_time)) service_completed = arrival_time + wait + service_duration - heappush(servers, service_completed) + heapreplace(servers, service_completed) print(f'Mean wait: {mean(waits):.1f} Max wait: {max(waits):.1f}') print('Quartiles:', [round(q, 1) for q in quantiles(waits)]) -- cgit v0.12