Python获取某一进程的CPU利用率的方法详解

import time
import psutil
 
_time = getattr(time, 'monotonic', time.time)
sum_cpus = psutil.cpu_count() or 1 #计算机的CPU核心数量，如果无法获取，则将核心数设置为1
 
def timer():
    return _time() * sum_cpus  #返回当前时间乘以CPU核心数量
 
pid_cpuinfo = {} #初始化一个空字典，用于存储进程ID与CPU信息的映射关系
 
def GetProcessCPU_Pre(id): #计算并返回给定进程ID的CPU利用率
    p = psutil.Process(id) #根据提供的进程ID,使用psutil库的Process类实例化一个进程对象
    tt = p.cpu_times()  # 获取进程的CPU时间信息
    st0, tt0_0, tt0_1 = pid_cpuinfo.get(id, (0, 0, 0))  # 获取之前保存的进程ID对应的CPU信息，初始时设定为0
    st1, tt1_0, tt1_1 = timer(), tt.user, tt.system #计算当前时间、进程用户态CPU时间和系统态CPU时间
 
    delta_proc = (tt1_0 - tt0_0) + (tt1_1 - tt0_1) #计算进程CPU时间的增量
    delta_time = st1 - st0 #计算时间增量
    try:
        cpus_percent = ((delta_proc / delta_time) * 100) #计算CPU利用率的百分比
    except:
        cpus_percent = 0.0
 
    pid_cpuinfo[id] = [st1, tt1_0, tt1_1] ##更新进程ID对应的CPU信息
    return "{:.2f}".format(cpus_percent) #返回格式化后的CPU利用率值，保留两位小数
 
# 输入需要检查的进程ID
process_id = 25400 #25400为我此时要计算cpu利用率的进程ID
result = GetProcessCPU_Pre(process_id)
print(result)

_timer = getattr(time, 'monotonic', time.time)
num_cpus = psutil.cpu_count() or 1
def timer():
    return _timer() * num_cpus
 
pid_cpuinfo = {}
def GetProcessCPU_Pre(id):
    p = psutil.Process(id)
    pt = p.cpu_times()
    st1,pt1_0,pt1_1 = timer(),pt.user,pt.system   # new
    st0,pt0_0,pt0_1 = pid_cpuinfo.get(id,(0,0,0)) # old
 
    delta_proc = (pt1_0 - pt0_0) + (pt1_1 - pt0_1)
    delta_time = st1 - st0
    try:
        cpus_percent = ((delta_proc / delta_time) * 100)
    except:
        cpus_percent = 0.0
 
    pid_cpuinfo[id] = [st1,pt1_0,pt1_1]
    return "{:.2f}".format(cpus_percent)

import time
from tkinter import simpledialog
import tkinter
import psutil
import os
 
root=tkinter.Tk()
root.withdraw()
 
pid=int(simpledialog.askstring(title="pid",prompt="输入进程号"))
p=psutil.Process(pid)
 
filename=p.name().split(".")[0]+"Process"+str(pid)+".csv"
#if os.path.exists("./"+filename):
#    os.remove("./"+filename)
 
# 文件第一行写入进程名
f=open("./"+filename,"a+")
f.write(p.name()+"\n")
f.write("TIME,%CPU,%MEM\n")
f.close()
 
# 循环记录时间、进程CPU利用率，内存占用
while True:
 
    f=open("./"+filename,"a+")
    current_time = time.strftime("%Y-%m-%d %H:%M:%S", time.localtime(time.time()))
    cpu_percent=p.cpu_percent()
    mem_percent=p.memory_percent()
    line=current_time+","+str(cpu_percent)+","+str(mem_percent)
    f.write(line+"\n")
    f.close()
    time.sleep(3)