Set thread names

To help with debugging

guix-data-service/jobs/load-new-guix-revision.scm

@@ -36,6 +36,8 @@
   #:use-module (guix packages)
   #:use-module (guix derivations)
   #:use-module (guix build utils)
+  #:use-module ((guix build syscalls)
+                #:select (set-thread-name))
   #:use-module (guix-data-service config)
   #:use-module (guix-data-service database)
   #:use-module (guix-data-service utils)
@@ -170,6 +172,11 @@ VALUES (nextval('" (log-part-sequence-name job_id) "'), $1, $2)")
      (setvbuf port-to-write-to 'line)
      (call-with-new-thread
       (lambda ()
+        (catch 'system-error
+          (lambda ()
+            (set-thread-name "inferior logging"))
+          (const #t))
+
         (with-postgresql-connection
          (simple-format #f "~A inferior error logging" job-id)
          (lambda (logging-conn)

guix-data-service/substitutes.scm

@@ -24,6 +24,8 @@
   #:use-module (fibers channels)
   #:use-module (guix substitutes)
   #:use-module (guix narinfo)
+  #:use-module ((guix build syscalls)
+                #:select (set-thread-name))
   #:use-module (guix-data-service utils)
   #:use-module (guix-data-service database)
   #:use-module (guix-data-service model build)
@@ -155,6 +157,11 @@
 
   (call-with-new-thread
    (lambda ()
+     (catch 'system-error
+       (lambda ()
+         (set-thread-name "request substitute query"))
+       (const #t))
+
      (while #t
        (with-exception-handler
            (lambda (exn)
@@ -196,6 +203,11 @@
 
   (call-with-new-thread
    (lambda ()
+     (catch 'system-error
+       (lambda ()
+         (set-thread-name "bulk substitute query"))
+       (const #t))
+
      (while #t
        (with-exception-handler
            (lambda (exn)