composer执行命令提示“已杀死”是什么情况？

composer require voku/simple_html_dom -vvv
Reading ./composer.json
Loading config file ./composer.json
Checked CA file /etc/pki/tls/certs/ca-bundle.crt: valid
Failed to initialize global composer: Composer could not find the config file: /home/admin/.composer/composer.json
To initialize a project, please create a composer.json file as described in the https://getcomposer.org/ "Getting Started" section
Reading /home/wwwroot/vendor/composer/installed.json
Loading plugin EasyWeChatComposer\Plugin
Loading plugin think\composer\Plugin
Running 1.7.2 (2018-08-16 16:57:12) with PHP 7.1.18 on Linux / 2.6.32-696.16.1.el6.x86_64
Downloading https://repo.packagist.org/packages.json
Writing /home/admin/.composer/cache/repo/https---repo.packagist.org/packages.json into cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/p-provider-2013.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/p-provider-2014.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/p-provider-2015.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/p-provider-2016.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/p-provider-2017.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/p-provider-2018.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/p-provider-2019-01.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/p-provider-2019-04.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/p-provider-2019-07.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/p-provider-2019-10.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/p-provider-archived.json from cache
Downloading http://repo.packagist.org/p/provider-latest%24502b160e3dcbe13f8c125df618d18632ebbad2402f1e07d96e00bf46c3da14ac.json
Writing /home/admin/.composer/cache/repo/https---repo.packagist.org/p-provider-latest.json into cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/provider-voku$simple-html-dom.json from cache
Using version ^4.7 for voku/simple_html_dom
./composer.json has been updated
Reading ./composer.json
Loading config file ./composer.json
Failed to initialize global composer: Composer could not find the config file: /home/admin/.composer/composer.json
To initialize a project, please create a composer.json file as described in the https://getcomposer.org/ "Getting Started" section
Reading /home/wwwroot/vendor/composer/installed.json
Loading plugin EasyWeChatComposer\Plugin_composer_tmp0
Loading plugin think\composer\Plugin_composer_tmp1
Reading ./composer.lock
Loading composer repositories with package information
Downloading https://repo.packagist.org/packages.json
Writing /home/admin/.composer/cache/repo/https---repo.packagist.org/packages.json into cache
Updating dependencies (including require-dev)
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/p-provider-2013.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/p-provider-2014.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/p-provider-2015.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/p-provider-2016.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/p-provider-2017.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/p-provider-2018.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/p-provider-2019-01.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/p-provider-2019-04.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/p-provider-2019-07.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/p-provider-2019-10.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/p-provider-archived.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/p-provider-latest.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/provider-adbario$php-dot-notation.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/provider-clagiordano$weblibs-configmanager.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/provider-danielstjules$stringy.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/provider-guzzlehttp$guzzle.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/provider-mtdowling$jmespath.php.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/provider-alibabacloud$client.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/provider-symfony$polyfill-mbstring.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/provider-guzzlehttp$psr7.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/provider-guzzlehttp$promises.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/provider-psr$http-message.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/provider-ralouphie$getallheaders.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/provider-aliyuncs$oss-sdk-php.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/provider-doctrine$cache.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/provider-easywechat-composer$easywechat-composer.json from cache
Reading /home/admin/.composer/cache/repo/https---repo.packagist.org/provider-symfony$options-resolver.json from cache

free -m
mkdir -p /var/_swap_
cd /var/_swap_
#Here, 1M * 2000 ~= 2GB of swap memory
dd if=/dev/zero of=swapfile bs=1M count=2000
mkswap swapfile
swapon swapfile
echo “/var/_swap_/swapfile none swap sw 0 0” >> /etc/fstab
#cat /proc/meminfo
free -m