Linux shell 实现队列并发任务
新建测试脚本：
vim concurrent-demo.sh
#!/bin/bash
#/*
# * Copyright 2017 ~ 2025 the original author or authors. <Wanglsir@gmail.com, 983708408@qq.com>
# *
# * Licensed under the Apache License, Version 2.0 (the "License");
# * you may not use this file except in compliance with the License.
# * You may obtain a copy of the License at
# *
# * http://www.apache.org/licenses/LICENSE-2.0
# *
# * Unless required by applicable law or agreed to in writing, software
# * distributed under the License is distributed on an "AS IS" BASIS,
# * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# * See the License for the specific language governing permissions and
# * limitations under the License.
# */
# 执行任务的函数
function run() {
local taskId=$1
local pfileFD=$2
echo "$(date '+%Y-%m-%d %H:%M:%S') - task ${taskId} running ..."
sleep 2
echo "$(date '+%Y-%m-%d %H:%M:%S') - task ${taskId} completed."
}
function executeTest() {
# 1. 定义相关变量
local concurrent=3 # 定义并发数, 在shell中叫 threadNum 不太合适, 因为是fork的子进程.
local pfile="/tmp/test.fifo" # 定义管道文件路径
local pfileFD="1234" # 定义管道文件的FD(文件句柄)
#local pfileFD="$RANDOM" # 若本函数需多次调用时, 测试：可使用shell内置random函数, 范围:[0-32767)，不建议在生成使用，生成环境建议使用seq序列，因为当CPU过高时可能导致系统随机源不足产生重复随机数，这会导致一系列问题
# 2. 创建Linux管道文件(写读数据会先进先出的队列, 类似java中Queue).
[ ! -p "$pfile" ] && mkfifo $pfile
eval "exec $pfileFD<>$pfile" # 创建文件句柄(fd), 除系统内置的0/1/2外的数字作为fd的标识即可, > 和 < 分别代表写读.
rm -f $pfile # 创建完fd后可删除管道文件
# 3. 初始化并发数, 即添加并发相同数量的换行符到FD, 用于后续读取换行符来控制并发数. (echo 默认标准输出换行符)
eval "for ((i=0;i<${concurrent};i++)); do echo ; done >&${pfileFD}"
# 4. 异步提交任务, 假设tasks数为10.
for i in `seq 1 10`; do
eval "read -u${pfileFD}" # 每次读一个, 读完一个就少一个(fifo队列)
{
run "$i" "$pfileFD" # (异步)调用真正执行任务的函数
eval "echo >&${pfileFD}" # 每执行完一个task, 继续又添加一个换行符, 目的是为了永远保持fd里有concurrent个标识, 直到任务执行完.
} &
done
wait
eval "exec ${pfileFD}>&-" # 关闭fd(管道文件)
exit 0
}
executeTest
执行测试：
2021-06-07 10:01:18 - task 1 running ...
2021-06-07 10:01:18 - task 2 running ...
2021-06-07 10:01:18 - task 3 running ...
2021-06-07 10:01:21 - task 1 completed.
2021-06-07 10:01:21 - task 2 completed.
2021-06-07 10:01:21 - task 3 completed.
2021-06-07 10:01:21 - task 4 running ...
2021-06-07 10:01:21 - task 5 running ...
2021-06-07 10:01:21 - task 6 running ...
2021-06-07 10:01:24 - task 4 completed.
2021-06-07 10:01:24 - task 5 completed.
2021-06-07 10:01:24 - task 6 completed.
2021-06-07 10:01:24 - task 7 running ...
2021-06-07 10:01:24 - task 8 running ...
2021-06-07 10:01:24 - task 9 running ...
2021-06-07 10:01:27 - task 8 completed.
2021-06-07 10:01:27 - task 7 completed.
2021-06-07 10:01:27 - task 9 completed.
2021-06-07 10:01:27 - task 10 running ...
2021-06-07 10:01:30 - task 10 completed.
