Raise Soft File Descriptor Limit Up To The Hard Limit (#10650)

* add changes

* comment

* kasey's review

Co-authored-by: prylabs-bulldozer[bot] <58059840+prylabs-bulldozer[bot]@users.noreply.github.com>

runtime/fdlimits/BUILD.bazel

@@ -0,0 +1,22 @@
+load("@prysm//tools/go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "go_default_library",
+    srcs = ["fdlimits.go"],
+    importpath = "github.com/prysmaticlabs/prysm/runtime/fdlimits",
+    visibility = ["//visibility:public"],
+    deps = [
+        "@com_github_ethereum_go_ethereum//common/fdlimit:go_default_library",
+        "@com_github_sirupsen_logrus//:go_default_library",
+    ],
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = ["fdlimits_test.go"],
+    deps = [
+        ":go_default_library",
+        "//testing/assert:go_default_library",
+        "@com_github_ethereum_go_ethereum//common/fdlimit:go_default_library",
+    ],
+)

runtime/fdlimits/fdlimits.go

@@ -0,0 +1,25 @@
+package fdlimits
+
+import (
+	"github.com/ethereum/go-ethereum/common/fdlimit"
+	log "github.com/sirupsen/logrus"
+)
+
+// SetMaxFdLimits is a wrapper around a few go-ethereum methods to allow prysm to
+// set its file descriptor limits at the maximum possible value.
+func SetMaxFdLimits() error {
+	curr, err := fdlimit.Current()
+	if err != nil {
+		return err
+	}
+	max, err := fdlimit.Maximum()
+	if err != nil {
+		return err
+	}
+	raisedVal, err := fdlimit.Raise(uint64(max))
+	if err != nil {
+		return err
+	}
+	log.Infof("Raised fd limit to %d from %d", raisedVal, curr)
+	return nil
+}

runtime/fdlimits/fdlimits_test.go

@@ -0,0 +1,22 @@
+package fdlimits_test
+
+import (
+	"testing"
+
+	gethLimit "github.com/ethereum/go-ethereum/common/fdlimit"
+	"github.com/prysmaticlabs/prysm/runtime/fdlimits"
+	"github.com/prysmaticlabs/prysm/testing/assert"
+)
+
+func TestSetMaxFdLimits(t *testing.T) {
+	assert.NoError(t, fdlimits.SetMaxFdLimits())
+
+	curr, err := gethLimit.Current()
+	assert.NoError(t, err)
+
+	max, err := gethLimit.Maximum()
+	assert.NoError(t, err)
+
+	assert.Equal(t, max, curr, "current and maximum file descriptor limits do not match up.")
+
+}