remove deprecated worker-pool-size option from configuration (pingcap#58)

* remove deprecated worker-pool-size option from configuration

* address comment

Author: holys

docs/tidb-lightning-user-guide.md

@@ -57,7 +57,7 @@ The following are the hardware requirements for deploying one set of TiDB Lighti
    - 16 GB+ memory
    - 1 TB+ SSD
    - 10 Gigabit network card
-   - Need to be deployed separately from the online business because TiDB Lighting fully consumes the CPU during runtime. Under certain circumstances, you can deploy it along with another component (like `tidb-server`) on one machine and configure to limit the CPU usage of `tidb-lightning`. See the `worker-pool-size` part in the first step of [Deploy `tidb-lightning`](#deploy-tidb-lightning). 
+   - Need to be deployed separately from the online business because TiDB Lighting fully consumes the CPU during runtime. Under certain circumstances, you can deploy it along with another component (like `tidb-server`) on one machine and configure to limit the CPU usage of `tidb-lightning`. See the `region-concurrency` part in the first step of [Deploy `tidb-lightning`](#deploy-tidb-lightning). 
 
 - tikv-importer
  
@@ -76,9 +76,9 @@ Under certain circumstances, you can deploy `tidb-lightning` and `tikv-importer`
 - 1 TB+ SSD
 - 10 Gigabit network card
 
-> **Note:** `tidb-lightning` is CPU intensive. If you use mixed deployment for it, you need to configure `worker-pool-size` to limit the number of occupied CPU cores of `tidb-lightning`. Otherwise other applications may be affected.
+> **Note:** `tidb-lightning` is CPU intensive. If you use mixed deployment for it, you need to configure `region-concurrency` to limit the number of occupied CPU cores of `tidb-lightning`. Otherwise other applications may be affected.
 
->   You can configure the `worker-pool-size` parameter of `tidb-lightning` to allocate 75% of CPU resources to `tidb-lightning`. For example, if CPU has 32 logical cores, you can set `worker-pool-size` to 24.
+>   You can configure the `region-concurrency` parameter of `tidb-lightning` to allocate 75% of CPU resources to `tidb-lightning`. For example, if CPU has 32 logical cores, you can set `region-concurrency` to 24.
 
 ### Prepare
 
@@ -168,9 +168,14 @@ For details, see [Deploy TiDB Using Ansible](https://pingcap.com/docs/op-guide/a
     # background profile for debugging ( 0 to disable )
     pprof-port = 10089
 
-    # change the concurrency number of data. It is set to the number of logical CPU cores by default and needs no configuration.
+
+    # table-concurrency controls the maximum handled tables concurrently while reading Mydumper SQL files. It can affect the tikv-importer memory usage amount.
+    table-concurrency = 8
+    # region-concurrency changes the concurrency number of data. It is set to the number of logical CPU cores by default and needs no configuration.
     # in mixed configuration, you can set it to 75% of the size of logical CPU cores.
-    # worker-pool-size =
+    # region-concurrency default to runtime.NumCPU()
+    # region-concurrency =  
+
 
     # logging
     level = "info"

lightning/config/config.go

@@ -61,7 +61,6 @@ func (c *Config) String() string {
 
 type Lightning struct {
 	common.LogConfig
-	WorkerPoolSize    int `toml:"worker-pool-size" json:"worker-pool-size"`
 	TableConcurrency  int `toml:"table-concurrency" json:"table-concurrency"`
 	RegionConcurrency int `toml:"region-concurrency" json:"region-concurrency"`
 	ProfilePort       int `toml:"pprof-port" json:"pprof-port"`
@@ -89,7 +88,6 @@ type TikvImporter struct {
 func NewConfig() *Config {
 	return &Config{
 		App: Lightning{
-			WorkerPoolSize:    runtime.NumCPU(),
 			RegionConcurrency: runtime.NumCPU(),
 			TableConcurrency:  8,
 		},

tidb-lightning.toml

@@ -4,9 +4,11 @@
 # background profile for debuging ( 0 to disable )
 pprof-port = 10089
 
-# number of workers to restore tables (default to `runtime.NumCPU()`).
-# worker-pool-size =
+
+# table-concurrency controls the maximum handled tables concurrently while reading Mydumper SQL files. It can affect the tikv-importer memory usage.
 table-concurrency = 8
+# region-concurrency changes the concurrency number of data. It is set to the number of logical CPU cores by default and needs no configuration.
+# In mixed configuration, you can set it to 75% of the size of logical CPU cores.
 # region-concurrency default to runtime.NumCPU()
 # region-concurrency =