1111A "normal" jobserver task, like the one initiated by a make subrocess would do:
1212
1313 - open read/write file descriptors to communicate with the job server;
14- - ask for one slot by calling:
14+ - ask for one slot by calling::
15+
1516 claim = os.read(reader, 1)
16- - when the job finshes, call:
17+
18+ - when the job finshes, call::
19+
1720 os.write(writer, b"+") # os.write(writer, claim)
1821
1922Here, the goal is different: This script aims to get the remaining number
2023of slots available, using all of them to run a command which handle tasks in
2124parallel. To to that, it has a loop that ends only after there are no
2225slots left. It then increments the number by one, in order to allow a
23- call equivalent to make -j$((claim+1)), e.g. having a parent make creating
26+ call equivalent to `` make -j$((claim+1))`` , e.g. having a parent make creating
2427$claim child to do the actual work.
2528
2629The end goal here is to keep the total number of build tasks under the
27- limit established by the initial make -j$n_proc call.
30+ limit established by the initial `` make -j$n_proc`` call.
2831
2932See:
3033 https://www.gnu.org/software/make/manual/html_node/POSIX-Jobserver.html#POSIX-Jobserver
@@ -40,21 +43,22 @@ class JobserverExec:
4043 Claim all slots from make using POSIX Jobserver.
4144
4245 The main methods here are:
46+
4347 - open(): reserves all slots;
4448 - close(): method returns all used slots back to make;
45- - run(): executes a command setting PARALLELISM=<available slots jobs + 1>
49+ - run(): executes a command setting PARALLELISM=<available slots jobs + 1>.
4650 """
4751
4852 def __init__ (self ):
49- """Initialize internal vars"""
53+ """Initialize internal vars. """
5054 self .claim = 0
5155 self .jobs = b""
5256 self .reader = None
5357 self .writer = None
5458 self .is_open = False
5559
5660 def open (self ):
57- """Reserve all available slots to be claimed later on"""
61+ """Reserve all available slots to be claimed later on. """
5862
5963 if self .is_open :
6064 return
@@ -118,7 +122,7 @@ def open(self):
118122 self .is_open = True
119123
120124 def close (self ):
121- """Return all reserved slots to Jobserver"""
125+ """Return all reserved slots to Jobserver. """
122126
123127 if not self .is_open :
124128 return
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