[no subject]

[Christopher Baines]

branch: master
commit b9031db946ff89a39e1507b430f64402b0e9572a
Author: Christopher Baines <address@hidden>
AuthorDate: Fri Jan 24 19:22:22 2020 +0000

    database: Enable running up to 4 database queries at once.
    
    The number of threads is copied from bin/cuirass.in. When you have at least
    two processors, this will allow database queries to be executed in parallel.
    
    With some crude testing using the Apache HTTP server benchmarking tool (ab
    from the httpd package), the max request latency does seem to drop when
    multiple threads are used, especially when the database queries are slow (I
    tested by adding usleep to the worker thread code).
    
    * src/cuirass/database.scm (with-database): Pass #:parallelism to
    make-worker-thread-channel.
---
 src/cuirass/database.scm | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/cuirass/database.scm b/src/cuirass/database.scm
index c82e306..7c1f286 100644
--- a/src/cuirass/database.scm
+++ b/src/cuirass/database.scm
@@ -439,7 +439,9 @@ worker thread that allows database operations to run 
without intefering with
 fibers."
   (parameterize ((%db-channel (make-worker-thread-channel
                                (lambda ()
-                                 (list (db-open))))))
+                                 (list (db-open)))
+                               #:parallelism
+                               (min (current-processor-count) 4))))
     body ...))
 
 (define* (read-quoted-string #:optional (port (current-input-port)))