make -jN warning: jobserver unavailable

[targos]

When compiling on the master branch, I have the following warning:

$ make -j8 V=
make[1]: warning: jobserver unavailable: using -j1.  Add '+' to parent make rule.
...

Is this a problem?

git bisect points to the following commit 4e2fa8b (@danbev):

4e2fa8b0dc1acd95f558cd5f123711b9cc936c72 is the first bad commit
commit 4e2fa8b0dc1acd95f558cd5f123711b9cc936c72
Author: Daniel Bevenius <daniel.bevenius@gmail.com>
Date:   Tue Aug 14 09:46:11 2018 +0200

    build: extract common code from NODE_EXE/_G_EXE
    
    This commit extracts common parts of the NODE_EXE, and NODE_G_EXE
    recipes into a canned reciepe to reduce some code duplication.
    
    PR-URL: https://github.com/nodejs/node/pull/22310
    Reviewed-By: Jon Moss <me@jonathanmoss.me>
    Reviewed-By: Minwoo Jung <minwoo@nodesource.com>
    Reviewed-By: Refael Ackermann <refack@gmail.com>
    Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
    Reviewed-By: Richard Lau <riclau@uk.ibm.com>

:100644 100644 3ca83bfed85ead088bd66568556d543c6a8d4602 f3372b096316af704589f6eae7ac3adbb9fec3c4 M	Makefile

[targos]

Extracted from the make documentation:

In order for make processes to communicate, the parent will pass information to the child. Since this could result in problems if the child process isn’t actually a make, the parent will only do this if it thinks the child is a make. The parent uses the normal algorithms to determine this (see How the MAKE Variable Works). If the makefile is constructed such that the parent doesn’t know the child is a make process, then the child will receive only part of the information necessary. In this case, the child will generate this warning message and proceed with its build in a sequential manner.

[danbev]

@targos I'll take a look at this hopefully later this afternoon or tomorrow morning.

[danbev]

@targos I don't get this warning locally and need to figure out what a change would look like but think reverting is the best option since the build time is affected. Thanks for bringing this to my attention!

[refack]

Fixed by: #22458