Use a ridiculous number of workers for parallel checkout

It would appear that even on a 2-core build agent, using 64 workers
leads to much faster checkout times than using a single worker, at least
on the Windows agents, which is what we're interested in here.

At some stage (somewhere between 64 and 92 workers in my tests), we risk
using too many resources, though, and the checkout fails. _Very fast_,
but it fails.

So let's try to strike a balance between getting fast and still staying
robust enough not to fail.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

src/git.ts

@@ -5,6 +5,17 @@ import {delimiter} from 'path'
 
 const gitForWindowsUsrBinPath = 'C:/Program Files/Git/usr/bin'
 
+/*
+ * It looks a bit ridiculous to use 56 workers on a build agent that has only
+ * a two-core CPU, yet manual testing revealed that 64 workers would be _even
+ * better_. But at 92 workers, resources are starved so much that the checkout
+ * is not only much faster, but also fails.
+ *
+ * Let's stick with 56, which should avoid running out of resources, but still
+ * is much faster than, say, using only 2 workers.
+ */
+const GIT_CONFIG_PARAMETERS = `'checkout.workers=56'`
+
 async function clone(
   url: string,
   destination: string,
@@ -24,6 +35,9 @@ async function clone(
       destination
     ],
     {
+      env: {
+        GIT_CONFIG_PARAMETERS
+      },
       stdio: [undefined, 'inherit', 'inherit']
     }
   )
@@ -85,6 +99,9 @@ export async function getViaGit(
           'git.exe',
           [`--git-dir=.tmp`, 'worktree', 'add', outputDirectory, id],
           {
+            env: {
+              GIT_CONFIG_PARAMETERS
+            },
             stdio: [undefined, 'inherit', 'inherit']
           }
         )
@@ -112,6 +129,7 @@ export async function getViaGit(
           ],
           {
             env: {
+              GIT_CONFIG_PARAMETERS,
               COMSPEC:
                 process.env.COMSPEC ||
                 `${process.env.WINDIR}\\system32\\cmd.exe`,