Add a subprocesses option for the dump command (#492)

Adds the ability to print out stack traces from subprocesses
when running the dump command, like we can already do for
the record / top commands

src/config.rs

@@ -253,7 +253,8 @@ impl Config {
             .arg(Arg::new("json")
                 .short('j')
                 .long("json")
-                .help("Format output as JSON"));
+                .help("Format output as JSON"))
+            .arg(subprocesses.clone());
 
         let completions = Command::new("completions")
             .about("Generate shell completions")
@@ -337,11 +338,11 @@ impl Config {
                 });
                 config.gil_only = matches.occurrences_of("gil") > 0;
                 config.include_idle = matches.occurrences_of("idle") > 0;
-                config.subprocesses = matches.occurrences_of("subprocesses") > 0;
             },
             _ => {}
         }
 
+        config.subprocesses = matches.occurrences_of("subprocesses") > 0;
         config.command = subcommand.to_owned();
 
         // options that can be shared between subcommands

src/dump.rs

@@ -1,12 +1,12 @@
-use console::style;
+use console::{Term, style};
 use failure::Error;
 
 use crate::config::Config;
 use crate::python_spy::PythonSpy;
 
 use remoteprocess::Pid;
 
-pub fn print_traces(pid: Pid, config: &Config) -> Result<(), Error> {
+pub fn print_traces(pid: Pid, config: &Config, parent: Option<Pid>) -> Result<(), Error> {
     let mut process = PythonSpy::new(pid, config)?;
     if config.dump_json {
         let traces = process.get_stack_traces()?;
@@ -18,10 +18,18 @@ pub fn print_traces(pid: Pid, config: &Config) -> Result<(), Error> {
         style(process.pid).bold().yellow(),
         process.process.cmdline()?.join(" "));
 
-    println!("Python v{} ({})\n",
+    println!("Python v{} ({})",
         style(&process.version).bold(),
         style(process.process.exe()?).dim());
 
+    if let Some(parentpid) = parent {
+        let parentprocess = remoteprocess::Process::new(parentpid)?;
+        println!("Parent Process {}: {}",
+            style(parentpid).bold().yellow(),
+            parentprocess.cmdline()?.join(" "));
+    }
+    println!("");
+
     let traces = process.get_stack_traces()?;
 
     for trace in traces.iter().rev() {
@@ -60,6 +68,21 @@ pub fn print_traces(pid: Pid, config: &Config) -> Result<(), Error> {
                 }
             }
         }
+
+        if config.subprocesses {
+            for (childpid, parentpid) in process.process.child_processes().expect("failed to get subprocesses") {
+                let term = Term::stdout();
+                let (_, width) = term.size();
+
+                println!("\n{}", &style("-".repeat(width as usize)).dim());
+                // child_processes() returns the whole process tree, since we're recursing here
+                // though we could end up printing grandchild processes multiple times. Limit down
+                // to just once
+                if parentpid == pid {
+                    print_traces(childpid, &config, Some(parentpid))?;
+                }
+            }
+        }
     }
     Ok(())
 }

src/main.rs

@@ -313,7 +313,7 @@ fn record_samples(pid: remoteprocess::Pid, config: &Config) -> Result<(), Error>
 fn run_spy_command(pid: remoteprocess::Pid, config: &config::Config) -> Result<(), Error> {
     match config.command.as_ref() {
         "dump" =>  {
-            dump::print_traces(pid, config)?;
+            dump::print_traces(pid, config, None)?;
         },
         "record" => {
             record_samples(pid, config)?;