Use Runtime.availableProcessors() as a default value for concurrentConnections

Author: worryg0d

core/src/main/java/com/instaclustr/esop/impl/AbstractOperationRequest.java

@@ -22,7 +22,7 @@ public abstract class AbstractOperationRequest extends OperationRequest {
         converter = StorageLocationTypeConverter.class,
         description = "Location to which files will be backed up or restored from, in form " +
             "cloudProvider://bucketName/clusterId/datacenterId/nodeId or file:///some/path/bucketName/clusterId/datacenterId/nodeId. " +
-            "'cloudProvider' is one of 's3', 'oracle', 'ceph', 'minio', 'azure' or 'gcp'.",
+            "'cloudProvider' is one of 's3', 'azure' or 'gcp'.",
         required = true)
     @JsonSerialize(using = StorageLocationSerializer.class)
     @JsonDeserialize(using = StorageLocationDeserializer.class)
@@ -48,8 +48,7 @@ public abstract class AbstractOperationRequest extends OperationRequest {
     public RetrySpec retry = new RetrySpec();
 
     @Option(names = {"--cc", "--concurrent-connections"},
-            description = "Number of files (or file parts) to download concurrently. Higher values will increase throughput. Default is 10.",
-            defaultValue = "10"
+            description = "Number of files (or file parts) to download / upload / hash concurrently. Higher values will increase throughput. Default is number of available CPUs."
     )
     @JsonProperty("concurrentConnections")
     public Integer concurrentConnections;
@@ -60,6 +59,8 @@ public abstract class AbstractOperationRequest extends OperationRequest {
 
     public AbstractOperationRequest() {
         // for picocli
+        if (concurrentConnections == null)
+            concurrentConnections = Runtime.getRuntime().availableProcessors();
     }
 
     public AbstractOperationRequest(final StorageLocation storageLocation,
@@ -74,7 +75,7 @@ public AbstractOperationRequest(final StorageLocation storageLocation,
         this.skipBucketVerification = skipBucketVerification;
         this.proxySettings = proxySettings;
         this.retry = retry == null ? new RetrySpec() : retry;
-        this.concurrentConnections = concurrentConnections == null ? 10 : concurrentConnections;
+        this.concurrentConnections = concurrentConnections == null ? Runtime.getRuntime().availableProcessors() : concurrentConnections;
         this.kmsKeyId = kmsKeyId;
     }