lncfg/workers: reduce default write pool workers to 8

Now that the write pool no longer executes blocking i/o operations, it
is safe to reduce this number considerably. The write pool now only
handles encoding and encryption of messages, making problem
computationally bound and thus dependent on available CPUs. The
descriptions of the workers configs is also updated to explain how users
should set these on their on machines.

lncfg/workers.go

@@ -9,7 +9,7 @@ const (
 
 	// DefaultWriteWorkers is the default maximum number of concurrent
 	// workers used by the daemon's write pool.
-	DefaultWriteWorkers = 100
+	DefaultWriteWorkers = 8
 
 	// DefaultSigWorkers is the default maximum number of concurrent workers
 	// used by the daemon's sig pool.
@@ -20,13 +20,13 @@ const (
 // pools.
 type Workers struct {
 	// Read is the maximum number of concurrent read pool workers.
-	Read int `long:"read" description:"Maximum number of concurrent read pool workers."`
+	Read int `long:"read" description:"Maximum number of concurrent read pool workers. This number should be proportional to the number of peers."`
 
 	// Write is the maximum number of concurrent write pool workers.
-	Write int `long:"write" description:"Maximum number of concurrent write pool workers."`
+	Write int `long:"write" description:"Maximum number of concurrent write pool workers. This number should be proportional to the number of CPUs on the host. "`
 
 	// Sig is the maximum number of concurrent sig pool workers.
-	Sig int `long:"sig" description:"Maximum number of concurrent sig pool workers."`
+	Sig int `long:"sig" description:"Maximum number of concurrent sig pool workers. This number should be proportional to the number of CPUs on the host."`
 }
 
 // Validate checks the Workers configuration to ensure that the input values are