lib/writeconcurrencylimiter: mention dependency on CPU cores for -maxConcurrentInserts flag

The change also removes misleading `default` value from README for `maxConcurrentInserts`
cmd-line flag.

Signed-off-by: hagen1778 <roman@victoriametrics.com>

README.md

@@ -2786,7 +2786,7 @@ Pass `-help` to VictoriaMetrics in order to see the list of supported command-li
   -loggerWarnsPerSecondLimit int
      Per-second limit on the number of WARN messages. If more than the given number of warns are emitted per second, then the remaining warns are suppressed. Zero values disable the rate limit
   -maxConcurrentInserts int
-     The maximum number of concurrent insert requests. Default value should work for most cases, since it minimizes the memory usage. The default value can be increased when clients send data over slow networks. See also -insert.maxQueueDuration (default 32)
+     The maximum number of concurrent insert requests. Default value depends on the number of CPU cores and should work for most cases since it minimizes the memory usage. The default value can be increased when clients send data over slow networks. See also -insert.maxQueueDuration
   -maxInsertRequestSize size
      The maximum size in bytes of a single Prometheus remote_write API request
      Supports the following optional suffixes for size values: KB, MB, GB, TB, KiB, MiB, GiB, TiB (default 33554432)

docs/Cluster-VictoriaMetrics.md

@@ -1136,7 +1136,7 @@ Below is the output for `/path/to/vminsert -help`:
   -loggerWarnsPerSecondLimit int
      Per-second limit on the number of WARN messages. If more than the given number of warns are emitted per second, then the remaining warns are suppressed. Zero values disable the rate limit
   -maxConcurrentInserts int
-     The maximum number of concurrent insert requests. Default value should work for most cases, since it minimizes the memory usage. The default value can be increased when clients send data over slow networks. See also -insert.maxQueueDuration (default 32)
+     The maximum number of concurrent insert requests. Default value depends on the number of CPU cores and should work for most cases since it minimizes the memory usage. The default value can be increased when clients send data over slow networks. See also -insert.maxQueueDuration
   -maxInsertRequestSize size
      The maximum size in bytes of a single Prometheus remote_write API request
      Supports the following optional suffixes for size values: KB, MB, GB, TB, KiB, MiB, GiB, TiB (default 33554432)
@@ -1696,7 +1696,7 @@ Below is the output for `/path/to/vmstorage -help`:
   -loggerWarnsPerSecondLimit int
      Per-second limit on the number of WARN messages. If more than the given number of warns are emitted per second, then the remaining warns are suppressed. Zero values disable the rate limit
   -maxConcurrentInserts int
-     The maximum number of concurrent insert requests. Default value should work for most cases, since it minimizes the memory usage. The default value can be increased when clients send data over slow networks. See also -insert.maxQueueDuration (default 32)
+     The maximum number of concurrent insert requests. Default value depends on the number of CPU cores and should work for most cases since it minimizes the memory usage. The default value can be increased when clients send data over slow networks. See also -insert.maxQueueDuration
   -memory.allowedBytes size
      Allowed size of system memory VictoriaMetrics caches may occupy. This option overrides -memory.allowedPercent if set to a non-zero value. Too low a value may increase the cache miss rate usually resulting in higher CPU and disk IO usage. Too high a value may evict too much data from the OS page cache resulting in higher disk IO usage
      Supports the following optional suffixes for size values: KB, MB, GB, TB, KiB, MiB, GiB, TiB (default 0)

docs/Single-server-VictoriaMetrics.md

@@ -2797,7 +2797,7 @@ Pass `-help` to VictoriaMetrics in order to see the list of supported command-li
   -loggerWarnsPerSecondLimit int
      Per-second limit on the number of WARN messages. If more than the given number of warns are emitted per second, then the remaining warns are suppressed. Zero values disable the rate limit
   -maxConcurrentInserts int
-     The maximum number of concurrent insert requests. Default value should work for most cases, since it minimizes the memory usage. The default value can be increased when clients send data over slow networks. See also -insert.maxQueueDuration (default 32)
+     The maximum number of concurrent insert requests. Default value depends on the number of CPU cores and should work for most cases since it minimizes the memory usage. The default value can be increased when clients send data over slow networks. See also -insert.maxQueueDuration
   -maxInsertRequestSize size
      The maximum size in bytes of a single Prometheus remote_write API request
      Supports the following optional suffixes for size values: KB, MB, GB, TB, KiB, MiB, GiB, TiB (default 33554432)

lib/writeconcurrencylimiter/concurrencylimiter.go

@@ -16,7 +16,7 @@ import (
 
 var (
 	maxConcurrentInserts = flag.Int("maxConcurrentInserts", 2*cgroup.AvailableCPUs(), "The maximum number of concurrent insert requests. "+
-		"Default value should work for most cases, since it minimizes the memory usage. The default value can be increased when clients send data over slow networks. "+
+		"Default value depends on the number of CPU cores and should work for most cases since it minimizes the memory usage. The default value can be increased when clients send data over slow networks. "+
 		"See also -insert.maxQueueDuration")
 	maxQueueDuration = flag.Duration("insert.maxQueueDuration", time.Minute, "The maximum duration to wait in the queue when -maxConcurrentInserts "+
 		"concurrent insert requests are executed")