前景提要
之前测试过一些电脑硬件、操作系统 Maven 编译时的性能对比：苹果 Apple MacBook M4 效率对比
最近刚入手一台龙芯电脑，于是测试一下 Maven 构建，发现有些 Java 项目在传统 CPU（amd64、arm64 等）可以正常编译构建，但是在龙芯上无法正常编译
问题发现
在龙芯 3A5000 执行 Nacos 2.5.0 标签编译时，出现异常
由下方异常可知，Maven 编译时，从 Maven 中央仓库（个人使用了国内腾讯云的 Maven 代理仓库）下载 kr.motd.maven:os-maven-plugin:1.5.0.Final 使用，然后
kr.motd.maven:os-maven-plugin:1.5.0.Final无法识别龙芯架构。
kr.motd.maven:os-maven-plugin的作用就是根据操作系统的名称，获取操作系统的架构。
及时升级到当前最新版 kr.motd.maven:os-maven-plugin:1.7.1
2022-11-07发布，也无法解决此问题
[root@anolis nacos]# mvn -e -V clean install -Dmaven.test.skip=true
Apache Maven 3.9.16 (2bdd9fddda4b155ebf8000e807eb73fd829a51d5)
Maven home: /srv/apache-maven-3.9.16
Java version: 1.8.0_492, vendor: Oracle Corporation, runtime: /srv/jdk8u492-b09/jre
Default locale: zh_CN, platform encoding: UTF-8
OS name: "linux", version: "6.6.102-5.3.3.an23.loongarch64", arch: "loongarch64", family: "unix"
[INFO] Error stacktraces are turned on.
[INFO] Scanning for projects...
Downloading from cloud-tencent: https://mirrors.cloud.tencent.com/nexus/repository/maven-public/kr/motd/maven/os-maven-plugin/1.5.0.Final/os-maven-plugin-1.5.0.Final.pom
Downloaded from cloud-tencent: https://mirrors.cloud.tencent.com/nexus/repository/maven-public/kr/motd/maven/os-maven-plugin/1.5.0.Final/os-maven-plugin-1.5.0.Final.pom (6.4 kB at 7.9 kB/s)
Downloading from cloud-tencent: https://mirrors.cloud.tencent.com/nexus/repository/maven-public/kr/motd/maven/os-maven-plugin/1.5.0.Final/os-maven-plugin-1.5.0.Final.jar
Downloaded from cloud-tencent: https://mirrors.cloud.tencent.com/nexus/repository/maven-public/kr/motd/maven/os-maven-plugin/1.5.0.Final/os-maven-plugin-1.5.0.Final.jar (29 kB at 43 kB/s)
[INFO] ------------------------------------------------------------------------
[INFO] Detecting the operating system and CPU architecture
[INFO] ------------------------------------------------------------------------
[INFO] os.detected.name: linux
[INFO] os.detected.arch: unknown
[INFO] os.detected.version: 6.6
[INFO] os.detected.version.major: 6
[INFO] os.detected.version.minor: 6
[ERROR] unknown os.arch: loongarch64 -> [Help 1]
org.apache.maven.MavenExecutionException: unknown os.arch: loongarch64
at kr.motd.maven.os.DetectExtension.afterProjectsRead (DetectExtension.java:95)
at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:223)
at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:173)
at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:101)
at org.apache.maven.cli.MavenCli.execute (MavenCli.java:919)
at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:285)
at org.apache.maven.cli.MavenCli.main (MavenCli.java:207)
at sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke (Method.java:498)
at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:255)
at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:201)
at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:362)
at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:314)
[ERROR]
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MavenExecutionException
[root@anolis nacos]#
解决方案
龙芯 Maven 仓库
- 龙芯平台Java应用迁移指南 · 文档
- https://maven.loongnix.cn/loongarchabi1/maven/：龙芯 Maven 仓库（兼容Linux 4.19内核）
- https://maven.loongnix.cn/loongarch/maven/：龙芯 Maven 仓库（兼容Linux5.10.0内核及以上）
龙芯官方针对于 无法在龙芯CPU中运行的 Maven 依赖进行了独立编译，并发布到龙芯自己的 Maven 仓库
在重新编译前，需要先删除本地 Maven 依赖
kr.motd.maven:os-maven-plugin:1.5.0.Final（从 Maven 中央仓库下载的依赖），编译时，由于设置了pluginRepositories、repositories，所以会优先从龙芯官方 Maven 仓库中下载
<pluginRepositories>
<pluginRepository>
<id>loongarch</id>
<name>Loongnix Maven Repository</name>
<url>https://maven.loongnix.cn/loongarch/maven/</url>
<releases>
<enabled>true</enabled>
</releases>
<snapshots>
<!-- 通常只需要 release 版本 -->
<enabled>false</enabled>
</snapshots>
</pluginRepository>
</pluginRepositories>
<repositories>
<repository>
<id>loongarch</id>
<name>Loongnix Maven Repository</name>
<url>https://maven.loongnix.cn/loongarch/maven/</url>
<releases>
<enabled>true</enabled>
</releases>
<snapshots>
<!-- 通常只需要 release 版本 -->
<enabled>false</enabled>
</snapshots>
</repository>
</repositories>
作者个人环境变量配置：
MAVEN_OPTS=-Dmaven.repo.local=/srv/apache-maven-repo，即：将本地 Maven 仓库地址设置为/srv/apache-maven-repo，优先级高于settings.xml中的<localRepository>/path/to/local/repo</localRepository>
# 查看本地存在的不支持 龙芯 的依赖
find /srv/apache-maven-repo/kr/motd/maven/os-maven-plugin/
# 删除本地存在的不支持 龙芯 的依赖
rm -rf /srv/apache-maven-repo/kr/motd/maven/os-maven-plugin/*
# 确认删除
find /srv/apache-maven-repo/kr/motd/maven/os-maven-plugin/
mvn -e -V clean install -Dmaven.test.skip=true
# 如果其他依赖也存在不兼容的情况，请同时删除依赖后再执行打包
[root@anolis nacos]# find /srv/apache-maven-repo/kr/motd/maven/os-maven-plugin/
/srv/apache-maven-repo/kr/motd/maven/os-maven-plugin/
/srv/apache-maven-repo/kr/motd/maven/os-maven-plugin/1.5.0.Final
/srv/apache-maven-repo/kr/motd/maven/os-maven-plugin/1.5.0.Final/os-maven-plugin-1.5.0.Final.jar.sha1
/srv/apache-maven-repo/kr/motd/maven/os-maven-plugin/1.5.0.Final/_remote.repositories
/srv/apache-maven-repo/kr/motd/maven/os-maven-plugin/1.5.0.Final/os-maven-plugin-1.5.0.Final.pom.sha1
/srv/apache-maven-repo/kr/motd/maven/os-maven-plugin/1.5.0.Final/os-maven-plugin-1.5.0.Final.pom
/srv/apache-maven-repo/kr/motd/maven/os-maven-plugin/1.5.0.Final/os-maven-plugin-1.5.0.Final.jar
[root@anolis nacos]# rm -rf /srv/apache-maven-repo/kr/motd/maven/os-maven-plugin/*
[root@anolis nacos]# find /srv/apache-maven-repo/kr/motd/maven/os-maven-plugin/
/srv/apache-maven-repo/kr/motd/maven/os-maven-plugin/
[root@anolis nacos]# mvn -e -V clean install -Dmaven.test.skip=true
Apache Maven 3.9.16 (2bdd9fddda4b155ebf8000e807eb73fd829a51d5)
Maven home: /srv/apache-maven-3.9.16
Java version: 1.8.0_492, vendor: Oracle Corporation, runtime: /srv/jdk8u492-b09/jre
Default locale: zh_CN, platform encoding: UTF-8
OS name: "linux", version: "6.6.102-5.3.3.an23.loongarch64", arch: "loongarch64", family: "unix"
[INFO] Error stacktraces are turned on.
[INFO] Scanning for projects...
Downloading from loongarch: https://maven.loongnix.cn/loongarch/maven/kr/motd/maven/os-maven-plugin/1.5.0.Final/os-maven-plugin-1.5.0.Final.pom
Downloaded from loongarch: https://maven.loongnix.cn/loongarch/maven/kr/motd/maven/os-maven-plugin/1.5.0.Final/os-maven-plugin-1.5.0.Final.pom (6.7 kB at 14 kB/s)
Downloading from loongarch: https://maven.loongnix.cn/loongarch/maven/kr/motd/maven/os-maven-plugin/1.5.0.Final/os-maven-plugin-1.5.0.Final.jar
Downloaded from loongarch: https://maven.loongnix.cn/loongarch/maven/kr/motd/maven/os-maven-plugin/1.5.0.Final/os-maven-plugin-1.5.0.Final.jar (29 kB at 333 kB/s)
[INFO] ------------------------------------------------------------------------
[INFO] Detecting the operating system and CPU architecture
[INFO] ------------------------------------------------------------------------
[INFO] os.detected.name: linux
[INFO] os.detected.arch: loongarch_64
[INFO] os.detected.version: 6.6
[INFO] os.detected.version.major: 6
[INFO] os.detected.version.minor: 6
[INFO] os.detected.release: anolis
[INFO] os.detected.release.version: 23.4
[INFO] os.detected.release.like.anolis: true
[INFO] os.detected.classifier: linux-loongarch_64
[WARNING] The project com.alibaba.nacos:nacos-all:pom:2.5.0 uses prerequisites which is only intended for maven-plugin projects but not for non maven-plugin projects. For such purposes you should use the maven-enforcer-plugin. See https://maven.apache.org/enforcer/enforcer-rules/requireMavenVersion.html
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Build Order:
[INFO]
[INFO] Alibaba NACOS 2.5.0 [pom]
[INFO] nacos-api 2.5.0 [jar]
[INFO] nacos-common 2.5.0 [jar]
[INFO] nacos-consistency 2.5.0 [jar]
[INFO] nacos-plugin 2.5.0 [pom]
[INFO] nacos-datasource-plugin 2.5.0 [jar]
[INFO] nacos-custom-environment-plugin 2.5.0 [jar]
[INFO] nacos-sys 2.5.0 [jar]
[INFO] nacos-persistence 2.5.0 [jar]
[INFO] nacos-auth-plugin 2.5.0 [jar]
[INFO] nacos-auth 2.5.0 [jar]
[INFO] nacos-trace-plugin 2.5.0 [jar]
[INFO] nacos-control-plugin 2.5.0 [jar]
[INFO] nacos-core 2.5.0 [jar]
[INFO] nacos-encryption-plugin 2.5.0 [jar]
[INFO] nacos-config-plugin 2.5.0 [jar]
[INFO] nacos-config 2.5.0 [jar]
[INFO] nacos-cmdb 2.5.0 [jar]
[INFO] nacos-naming 2.5.0 [jar]
[INFO] nacos-address 2.5.0 [jar]
[INFO] nacos-logger-adapter-impl 2.5.0 [pom]
[INFO] nacos-logback-adapter-12 2.5.0 [jar]
[INFO] nacos-log4j2-adapter 2.5.0 [jar]
[INFO] nacos-client 2.5.0 [jar]
[INFO] nacos-plugin-default-impl 2.5.0 [pom]
[INFO] nacos-default-auth-plugin 2.5.0 [jar]
[INFO] nacos-default-control-plugin 2.5.0 [jar]
[INFO] nacos-default-plugin-all [jar]
[INFO] nacos-istio 2.5.0 [jar]
[INFO] nacos-prometheus 2.5.0 [jar]
[INFO] nacos-console 2.5.0 [jar]
[INFO] nacos-test 2.5.0 [pom]
[INFO] nacos-config-test 2.5.0 [jar]
[INFO] nacos-naming-test 2.5.0 [jar]
[INFO] nacos-core-test 2.5.0 [jar]
[INFO] nacos-example 2.5.0 [jar]
[INFO] nacos-distribution 2.5.0 [pom]
......
龙芯大客户解决方案
如果大规模使用龙芯服务器执行 Maven 项目编译，上述方案并不成熟，因为速度慢，影响执行效率：存在两个仓库，并且龙芯仓库优先级高，除了极少数的 Maven 依赖使用一个 Maven 仓库（龙芯仓库）下载外，其他不在 龙芯 Maven 仓库中的依赖，依然会先访问 龙芯 Maven 仓库，再访问 Maven 中央仓库
龙芯官方 Maven 仓库的速度慢
虽然可以在一台机器上使用同一个 Maven 本地仓库，但是对于自动化 CI/CD 依赖变更时问题排查不利（非常细节的内容，不在意可不关注）
[INFO] --------------------< com.alibaba.nacos:nacos-all >---------------------
[INFO] Building Alibaba NACOS 2.5.0 2.5.0 [1/37]
[INFO] from pom.xml
[INFO] --------------------------------[ pom ]---------------------------------
Downloading from loongnix: https://maven.loongnix.cn/loongarch/maven/org/apache/maven/plugins/maven-enforcer-plugin/3.5.0/maven-enforcer-plugin-3.5.0.pom
Downloading from cloud-tencent: https://mirrors.cloud.tencent.com/nexus/repository/maven-public/org/apache/maven/plugins/maven-enforcer-plugin/3.5.0/maven-enforcer-plugin-3.5.0.pom
Downloaded from cloud-tencent: https://mirrors.cloud.tencent.com/nexus/repository/maven-public/org/apache/maven/plugins/maven-enforcer-plugin/3.5.0/maven-enforcer-plugin-3.5.0.pom (8.1 kB at 3.4 kB/s)
Downloading from loongnix: https://maven.loongnix.cn/loongarch/maven/org/apache/maven/enforcer/enforcer/3.5.0/enforcer-3.5.0.pom
Downloading from cloud-tencent: https://mirrors.cloud.tencent.com/nexus/repository/maven-public/org/apache/maven/enforcer/enforcer/3.5.0/enforcer-3.5.0.pom
Downloaded from cloud-tencent: https://mirrors.cloud.tencent.com/nexus/repository/maven-public/org/apache/maven/enforcer/enforcer/3.5.0/enforcer-3.5.0.pom (9.3 kB at 23 kB/s)
Downloading from loongnix: https://maven.loongnix.cn/loongarch/maven/org/apache/maven/maven-parent/42/maven-parent-42.pom
Downloading from cloud-tencent: https://mirrors.cloud.tencent.com/nexus/repository/maven-public/org/apache/maven/maven-parent/42/maven-parent-42.pom
Downloaded from cloud-tencent: https://mirrors.cloud.tencent.com/nexus/repository/maven-public/org/apache/maven/maven-parent/42/maven-parent-42.pom (50 kB at 191 kB/s)
Downloading from loongnix: https://maven.loongnix.cn/loongarch/maven/org/apache/apache/32/apache-32.pom
Downloading from cloud-tencent: https://mirrors.cloud.tencent.com/nexus/repository/maven-public/org/apache/apache/32/apache-32.pom
Downloaded from cloud-tencent: https://mirrors.cloud.tencent.com/nexus/repository/maven-public/org/apache/apache/32/apache-32.pom (24 kB at 63 kB/s)
Downloading from loongnix: https://maven.loongnix.cn/loongarch/maven/org/apache/maven/plugins/maven-enforcer-plugin/3.5.0/maven-enforcer-plugin-3.5.0.jar
Downloading from cloud-tencent: https://mirrors.cloud.tencent.com/nexus/repository/maven-public/org/apache/maven/plugins/maven-enforcer-plugin/3.5.0/maven-enforcer-plugin-3.5.0.jar
Downloaded from cloud-tencent: https://mirrors.cloud.tencent.com/nexus/repository/maven-public/org/apache/maven/plugins/maven-enforcer-plugin/3.5.0/maven-enforcer-plugin-3.5.0.jar (39 kB at 21 kB/s)
......
- 基于 Nexus 等软件，创建一个 Maven 中央仓库的代理仓库（可以直接使用 https://repo1.maven.org/maven2/ ，或者国内云厂商的地址，见：Maven 仓库地址 ）
- 国内云厂商 Maven 代理仓库 更新频率通常在 1 天左右，可能无法及时下载到最新版
- 建议使用 https://repo1.maven.org/maven2/ 做一个候补
- 基于 Nexus 等软件，创建一个 龙芯官方 Maven 代理仓库
- 基于 Nexus 等软件，创建一个 Maven 合并仓库，合并仓库包含上述 Maven 代理仓库，并且将 龙芯官方 Maven 代理仓库左右第一优先级
- 首次下载某个依赖时，会通过 龙芯官方 Maven 代理仓库，访问龙芯官方 Maven 仓库，不存在时再访问 Maven 中央仓库的代理仓库，后续再下载同一依赖时，Maven 合并仓库直接返回 Maven 中央仓库的代理仓库已经缓存的依赖
- 可能遇见的问题：推荐在龙芯电脑上构建 Maven 项目时，使用 Maven 代理仓库：避免 龙芯 Maven 仓库无法下载等问题